OMAHA, Neb. (AP) — Police are trying to find out who tossed a boulder through glass on a door at the Omaha Islamic Center.

Police say some people began throwing stones at the center in north-central Omaha a little before 3:30 a.m. Sunday. Images from a security camera show one of the people heaving the 40-pound boulder through the door glass. No injuries or arrests have been reported.

Leaders at the center say the attack was the first in 20 years.

The Council on American-Islamic Relations on Monday called for state and federal authorities to investigate the incident as a possible hate crime and for police to increase protection at the mosque.