By PATTY NIEBERG and THOMAS PEIPERT

BOULDER, Colo. (AP) — A shooting at a crowded Colorado supermarket that killed 10 people, including the first police officer to arrive, sent terrorized shoppers and workers scrambling for safety and stunned a state that has grieved several mass killings. A lone suspect was in custody, authorities said.

Hundreds of police officers from throughout the Denver metropolitan area responded to the Monday afternoon attack, converging on a King Soopers supermarket in a busy shopping plaza in southern Boulder. SWAT officers carrying ballistic shields slowly approached the store as others quickly escorted frightened people away from the building, some of its windows shattered. Customers and employees fled through a back loading dock to safety. Others took refuge in nearby shops.

One suspect was in custody, a tearful Boulder Police Chief Maris Herold said late Monday. Authorities didn’t identify the suspect, though Boulder County District Attorney Michael Dougherty said the suspect was the only person injured and was receiving medical care.

Officers had escorted a shirtless man in handcuffs, blood running down his leg, from the store during the siege. Authorities would not say if he was the suspect. Foothills Hospital in Boulder was treating one person from the shooting scene but refused further comment, said Rich Sheehan, spokesman for Boulder Community Health, which operates the hospital.

“This is a tragedy and a nightmare for Boulder County,” Dougherty said. “These were people going about their day, doing their shopping. I promise the victims and the people of the state of Colorado that we will secure justice.”

Herold identified the slain officer as Eric Talley, 51, who had been with Boulder police since 2010. He was the first to arrive after responding to a call about shots fired and someone carrying a rifle, she said.

“He was by all accounts one of the outstanding officers of the Boulder Police Department, and his life was cut too short,” Dougherty said.

Dozens of police and emergency vehicles, their lights flashing, escorted an ambulance carrying the officer from the shooting scene after nightfall. Some residents stood along the route, their arms raised in salute.

Identities of the other nine victims were not disclosed as police were still notifying their family members.

Dougherty said it was too early to speculate on a motive and that the investigation involving local, state and federal agencies would take days.

The attack in Boulder, about 25 miles (40 kilometers) northwest of Denver and home to the University of Colorado, stunned a state that has seen several mass shootings, including the 1999 Columbine High School massacre and the 2012 Aurora movie theater shooting.

Monday’s midafternoon attack was the seventh mass killing this year in the U.S., following the March 16 shooting that left eight people dead at three Atlanta-area massage businesses, according to a database compiled by The Associated Press, USA Today and Northeastern University.

It follows a lull in mass killings during the pandemic in 2020, which had the smallest number of such attacks in more than a decade, according to the database, which tracks mass killings defined as four or more dead, not including the shooter.

Dean Schiller said he had just left the supermarket when he heard gunshots. He saw three people lying face down — one in a doorway and two in the parking lot. Schiller said he couldn’t tell if they were breathing.

Sarah Moonshadow and her son, Nicolas Edwards, had just bought strawberries when they heard gunfire. Moonshadow told The Denver Post they ducked and “just ran.” Outside, Edwards said, arriving police pulled up next to a body in the parking lot.

“I knew we couldn’t do anything for the guy,” he said. “We had to go.”

Video posted on YouTube showed one person on the floor inside the store and two more outside on the ground. What sounds like two gunshots are heard at the beginning of the video.

Investigators had just started sorting through the crime scene and conducting witness interviews, Dougherty said. Matthew Kirsch, the acting U.S. attorney for Colorado, pledged that “the full weight of federal law enforcement” will support the investigation. He said investigators from the Bureau of Alcohol, Tobacco, Firearms and Explosives were at the crime scene, along with FBI agents.

White House press secretary Jen Psaki tweeted that President Joe Biden had been briefed on the shooting. Gov. Jared Polis, meanwhile, said in a statement that “Today we saw the face of evil. I am grieving with my community and all Coloradans.” The King Soopers chain said in a statement that it was offering prayers and support “to our associates, customers, and the first responders who so bravely responded to this tragic situation.”

___

Associated Press writers Colleen Slevin and Jim Anderson in Denver contributed. Nieberg is a corps member for the Associated Press/Report for America Statehouse News Initiative. Report for America is a nonprofit national service program that places journalists in local newsrooms to report on undercovered issues.

By MARIA CHENG and LAURAN NEERGAARD

LONDON (AP) — AstraZeneca’s COVID-19 vaccine provided strong protection against sickness and eliminated hospitalizations and deaths from the disease across all age groups in a late-stage study in the United States, the company announced Monday.

AstraZeneca said its experts did not identify any safety concerns related to the vaccine, including finding no increased risk of rare blood clots identified in Europe.

Although AstraZeneca’s vaccine has been authorized in more than 50 countries, it has not yet been given the green light in the U.S. — and has struggled to gain public trust amid a troubled rollout. The study comprised more than 30,000 volunteers, of whom two-thirds were given the vaccine while the rest got dummy shots.

In a statement, AstraZeneca said its COVID-19 vaccine was 79% effective at preventing symptomatic COVID-19 and was 100% effective in stopping severe disease and hospitalization, though it has not yet published full data. Investigators said the vaccine worked across all ages, including older people — something experts wanted better data on. Two doses of the AstraZeneca vaccine were given to people four weeks apart.

“These findings reconfirm previous results observed,” said Ann Falsey, of the University of Rochester School of Medicine, who helped lead the trial. “It’s exciting to see similar efficacy results in people over 65 for the first time.”

The AstraZeneca shot is a pillar of a U.N.-backed project known as COVAX that aims to get COVID-19 vaccines to poorer countries, and it has also become a key tool in European countries’ efforts to boost their sluggish vaccine rollouts.

Dr. Paul Hunter, a professor of medicine at the University of East Anglia, said the results were reassuring but that more details were needed to back up AstraZeneca’s claim that the vaccine was completely effective at preventing severe disease and hospitalization.

”It would be good to know how many severe cases occurred in the control group and so what the confidence intervals are for this 100% figure,” said Hunter, who was not connected to the study. “But this should add confidence that the vaccine is doing what it is most needed for.”

The early findings from the U.S. study are just one set of information AstraZeneca must submit to the Food and Drug Administration. An FDA advisory committee will publicly debate the evidence behind the shots before the agency decides whether to allow emergency use of the vaccine. In the past, the time between a company revealing efficacy data and a shot being authorized in the U.S. has been about a month.

Stephen Evans, of the London School of Hygiene & Tropical Medicine, said the new data is important for two reasons: The findings will reassure the FDA, which is reluctant to rely on data obtained outside the United States, but they could also boost confidence more broadly in the shot.

“The benefits of these results will mainly be for the rest of the world where confidence in the AZ (AstraZeneca) vaccine has been eroded, largely by political and media comment,” he said.

Scientists had hoped the U.S. study would clear up some of the confusion about just how well the shots really work, particularly in older people. Previous research suggested the vaccine was effective in younger populations, but there was no solid data proving its efficacy in those over 65, often those most vulnerable to COVID-19.

Britain first authorized the vaccine based on partial results from testing in the United Kingdom, Brazil and South Africa that suggested the shots were about 70% effective. But those results were clouded by a manufacturing mistake that led some participants to get just a half dose in their first shot — an error the researchers didn’t immediately acknowledge.

Then came more questions, about how well the vaccine protected older adults and how long to wait before the second dose. Some European countries including Germany, France and Belgium initially withheld the shot from older adults and only reversed their decisions after new data suggested it was offering seniors protection.

AstraZeneca’s vaccine development was rocky in the U.S., too. Last fall, the FDA suspended the company’s study for an unusual six weeks, as frustrated regulators sought information about some neurologic complaints reported in Britain; ultimately, there was no evidence the vaccine was to blame.

Last week, more than a dozen countries, mostly in Europe, temporarily suspended their use of the AstraZeneca shot after reports it was linked to rare blood clots — even as international health agencies insisted the benefits of the vaccine outweighed the risks. On Thursday, the European Medicines Agency concluded after an investigation that the vaccine did not raise the overall risk of blood clots, but could not rule out that it was connected to two very rare types of clots. It recommended adding a warning about these cases to the vaccine’s leaflet.

It’s not unheard of for such rare problems to crop up as vaccines are rolled out since trials typically look at tens of thousands of people, and some issues are only seen once the shot is used in millions of people.

France, Germany, Italy and other countries subsequently resumed their use of the shot on Friday, with senior politicians rolling up their sleeves to show the vaccine was safe.

AstraZeneca said it would continue to analyze the U.S. data before submitting it to the FDA in the coming weeks. It said the data would also soon be published in a peer-reviewed journal.

The AstraZeneca shot is what scientists call a “viral vector” vaccine. The shots are made with a harmless virus, a cold virus that normally infects chimpanzees. It acts like a Trojan horse to carry the coronavirus’s spike protein’s genetic material into the body that in turn produces some harmless protein. That primes the immune system to fight if the real virus comes along.

Two other companies, Johnson & Johnson and China’s CanSino Biologics, make COVID-19 vaccines using the same technology but using different cold viruses.

___

Neergaard reported from Washington.

___

Follow AP’s pandemic coverage at https://apnews.com/hub/coronavirus-pandemic, https://apnews.com/hub/coronavirus-vaccine and https://apnews.com/UnderstandingtheOutbreak.