A fire ripped through an apartment building in District Heights Tuesday night, leaving dozens of residents displaced but none injured, officials said.

Around 7:45 p.m., a Prince George’s County police officer saw a column of smoke from a distance, and tracked down the source to a three-story apartment building in the 1900 block of Rochelle Avenue.

The officer, who was not identified, reported the fire to dispatchers and began knocking on apartment doors, telling residents to evacuate.

According to fire department spokesman Mark Brady, the fire had spread to all three floors and the attic of the building. Investigators did not say where the fire may have started.

It took 75 firefighters about one hour to put out the blaze, Brady said. The cause remains under investigation.

No injuries were reported, but 21 units were affected and about 30 residents are displaced. A temporary shelter has been opened at Central High School, Brady said.