A three-alarm fire broke out at a multi-story apartment building in downtown Oakland Monday morning, officials said.

Around 7:15 a.m., the Oakland Fire Department said crews were responding to a three-alarm incident at the corner of 19th and Broadway. About 50 firefighters are on scene.

A fire department spokesperson told CBS News Bay Area, that the building is being evacuated and that interior rescue operations were taking place.

Three people were treated and transported to a hospital for smoke inhalation. One firefighter suffered a minor injury.  

Firefighters said the incident was placed under control around 8:40 a.m. The cause of the fire was not immediately known. 

Traffic on Broadway remains blocked between 17th and 20th streets as of 8:55 a.m. Additional details were not immediately available.