Philadelphia police are hunting for two suspects who stole over 40 industrial propane tanks from a distributor, and they’ve called in the Department of Homeland Security to aid in the investigation.

Surveillance footage of the first theft that occurred on Deccember 16 at the Praxair, Welding Gas and Supply Center shows “a suspect organizing the tanks, then a Dodge or Chrysler minivan pulls up and the two suspects load the vehicle,” ABC 6 reports.

A second vehicle acting as a lookout can be seen pulling into the parking lot, and then pulls away. A suspect then emerges from out-of-camera view and hops the razor-wire fence, and later cuts a hole in the fence so the minivan can pull in.

It is clear from the video the thieves were precise and the operation was well planned.

“When you talk about the quantity that’s been taken, there’s been like 40-something tanks taken, that adds up to a lot of propane that would last you a long time so that’s what we are worried about,” says Lt. Dennis Rosenbaum of Northeast Detectives.

Investigators believe the thefts are for money, but given the number of tanks involved, they’re also looking at the potential for terrorism.

“What’s concerning about some of the sizes of these propane tanks are 100-pound tanks, which hold 100 pounds of propane each,” Rosenbaum says.

According to Rosenbaum, propane prices are at historic lows, so they believe there’s the possibility something more sinister may be afoot.

WTRF reports the Department of Homeland Security was brought in “out of an abundance of caution.”

Rosenbaum says they’re treating them as industrial thefts, “unless we come up with something else.”

Watch the surveillance footage here: