Two construction workers were trapped atop a cherry picker truck while working outside of a Northwest Washington school and D.C. firefighters were preparing to rescue them, authorities said.

Rescue crews were called to Key Elementary School in the 5000 block of Dana Place and found the workers trapped about 15 feet above a roof of the building about 5:45 p.m., said Pete Piringer, a spokesman. The workers were inside the bucket of a cherry picker, which was wedged against the building’s chimney, authorities said.

Rescuers were expected to use an aerial ladder to rescue the workers, who were not reported injured.