KEOKUK, Iowa (AP) — Investigators are trying to determine what caused a major downtown fire in the southeast Iowa town of Keokuk.

KHQA reports (http://bit.ly/2hi1CFQ ) the fire was reported around 11:30 p.m. Monday.

Initially, some people were trapped on the roof of the building, but a neighbor helped them escape the building before firefighters arrived.

Fire Chief Gabe Rose says flames were coming out of a second-floor window when crews arrived, but firefighters were able to control the blaze quickly.

Rose says someone may have been doing some furniture work on the second floor before the fire, but investigators are still trying to determine the cause.

One person sustained minor injuries in the fire and was treated at a local hospital.