OAKLAND (CBS SF) — Authorities are investigating after a recycling truck driver was injured Tuesday morning when an explosion happened in the back of his vehicle in Oakland, officials said.

Oakland police spokeswoman Officer Johnna Watson said the explosion took place at 7:55 a.m. near Moss Avenue and Harrison Street. The explosion occurred in the rear of the truck while the load was being loaded and crushed.

Oakland police officers and the Alameda County bomb squad rushed to the scene to investigate the incident. Neither the bomb squad nor Cal Waste Solutions officials could determine what combusted.

A witness told police the force of the explosion tossed the California Waste Solutions driver into the air. He was rushed to Highland Hospital, but was released in the afternoon.

A camera mounted on the back of the truck shot video that showed the driver getting blown back by the explosion and and into a recycling container before falling to the ground.

“Thankfully, there were neighbors in the area that immediately responded and assisted him and stayed here with him until emergency personnel arrived,” said California Waste Solutions spokesperson Tasion Kwamilele.

“The safety of our employees is of the upmost importance and we will continue working with local officials as the circumstances surrounding this incident are investigated.”

Kwamilele explained that placing hazardous materials like propane tanks and batteries in recycling containers, where compression from machines is happening, can be prone to such explosions.

Jed Eastep, a neighbor in the area, described the moment the explosion occurred.

“I’ve never seen anything explode like that just out of the trash,” he said. “It seemed way too powerful to have been just a battery exploding or something like that.”

Chopper 5 flew over the truck after it was escorted by police to a recycling center to be inspected.

Police said there was still no word on what caused the explosion.

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