Homes being evacuated after derailment north of Philadelphia

Homes were being evacuated in Whitemarsh Township north of Philadelphia early Monday after a train derailment.

Officials said that just before 5 a.m., part of a 40-car freight train derailed. At least 10 of the cars are said to be off the tracks.

Hazmat crews have been called in. 

There's no word on what's in the derailed cars.