Rubble following a building collapse is seen in this aerial still image taken from video courtesy of NBC10.com, in Philadelphia June 5, 2013. An industrial building collapsed in downtown Philadelphia on Wednesday and rescue workers rushed to the scene to investigate the damage and determine whether there were any victims, police said.[Photo/Agencies]

WASHINGTON - A building has collapsed in the US city of Philadelphia, with up to 10 people believed to be trapped under the rubble, US media reported Wednesday.

The four-story building, reportedly housing residential apartments, collapsed at around 10:45 am local time in the downtown area of Philadelphia. Initial reports indicate eight to 10 people may be trapped under the debris.

Philadelphia rescue crews have responded to the incident. Dozens of firefighters and emergency personnel are at the scene searching for victims.

It remains unclear what caused the collapse. The residential building was reportedly being demolished at the time of the collapse, CBS Philadelphia reported.

Some victims have been transported to nearby trauma centers.

The building next door was undergoing demolition, but it is not immediately clear if there is any connection, Fox News reported.

Firefighters and rescue workers search through rubble following a building collapse in Philadelphia June 5, 2013. A building collapsed in downtown Philadelphia on Wednesday, killing a 35-year-old woman and injuring 13 other people under in mountains of crushed concrete and splintered wood, officials said. [Photo/Agencies]