DEEP RIVER, Conn. -- Firefighters from four towns were called to a blaze at a Deep River trucking company Thursday.

The blaze broke out at Stalsburg Express on Route 154 at about noon.

Volunteer firefighters from Deep River, Essex, Chester and Killingworth were called to the scene.

"When we got here, it was totally fully involved and we had multiple explosions," said Deep River Fire Chief Peter Woodcock.

While investigators hadn't identified the source of the explosions Thursday evening, they said it was most likely fuel or propane tanks.

They said there were several small explosions and one big one.

"We had a major one … a big fireball to the top of the trees," Woodcock said.

The company had seven tractor-trailers and box trucks. All but one of the trucks were on the road when the fire hit.

"I could actually see it from my house when I left and they could see it from Old Saybrook Auto Mall, so it was going," WoodCock said.

The Department of Environmental Protection was called to the scene amid concerns of runoff from the fire reaching nearby pond and eventually making it into the river.

"We called the DEP. We have a lot of oil and fluids running down the driveway and we've had town crews down there with sand," Woodcock said. "They're trying to dike up everything."