Arizona Train Derailment Ignites Massive Fire, Bridge Partially Collapses 

A massive fire is burning near Phoenix, Arizona, on Wednesday morning following a freight train derailment on a bridge. 

Union Pacific said at least ten cars derailed on a bridge over Tempe Town Lake at 6:15 am, reported CBS 5 Phoenix

Video from social media shows scenes of the train derailment on the bridge. Tempe firefighters, paramedics, and police have arrived at the incident area. 

"This is a coordinated attack with several agencies fighting the fire involving multiple train cars," Tempe police Det. Natalie Barela said in a statement, quoted by NBC News.

"The cause of the derailment has not been identified. This is a very fluid and active scene," said Barela.

Tempe Fire Medical Rescue told Fox News multiple train cars carrying lumber were on fire, describing the incident as a second-alarm. 

An aerial view shows a partial bridge collapse over Tempe Town Lake. 

It's not yet clear what caused the train derailment.