Officials reveal what was in freight train cars that derailed in Whitemarsh Twp.

WHITEMARSH TWP., Pennsylvania (WPVI) -- The investigation continues into what caused a CSX freight train to derail in Montgomery County, Pennsylvania on Monday morning.

According to officials, the crash happened at about 4:50 a.m. near the intersection of Stenton Avenue and Joshua Road in Whitemarsh Township.

The 40-car CSX train was operating on Norfolk Southern tracks.

A total of 15 cars derailed. Eight of the cars that went off the tracks were empty.

Five cars contained urea, a liquid fertilizer. Another car contained tetrachloroethylene, a degreaser chemical used in dry cleaning, which the EPA says is a carcinogen.

One car contained silicone pellets, which spilled out on the ground.

"The total weight of the car is 190,000 pounds. That's a lot of pellets that need to be cleaned up. And that will be something that we'll be watching with the railroad as well," said Ben Russell of the Pennsylvania Department of Environmental Protection.

Officials say no hazardous materials leaked from the train cars.

"As of now, the only thing that is leaking from any of the rail cars involved is silicone pellets, which pose no risk to the community," police said.

Officials said precautionary evacuations occurred at 12 residences closest to the scene.

"I thought, 'is this real?'" said Jennifer Rosenstein, who was one of the people evacuated.

"We were just totally shocked and we didn't know when we'd be allowed back in, so we didn't know what to bring, or what to do," she said.

Residents were able to get back into their homes by 9:30 a.m.

There were no injuries in the derailment and there was no ongoing hazard to the public.

The NTSB is investigating as environmental and construction crews work to carefully upright and remove the derailed cars.

The train does have recorders on board to help in the investigation.