IOWA CITY, Iowa (AP) — Hundreds of protesters angry about Donald Trump’s presidential win blocked Interstate 80 in Iowa City for about a half-hour, backing up traffic for miles.

The protests began Friday afternoon when about 200 high school students walked out of class and held a rally on the University of Iowa campus, dubbed a “Not My America” protest. University students joined the protest and listened to speeches before marching through downtown and down Dubuque Street toward the freeway.

Protesters walked out onto I-80 about 5 p.m. Iowa City police and state troopers held back traffic but didn’t intervene in the protests.

Protesters dispersed about a half-hour later and walked toward downtown.

The protest caused huge traffic snarls on the freeway and Dubuque Street.