At least four people were killed and 14 others injured after a church van crashed into a pickup truck and caught fire in Hyattsville, Md. on Sunday, according to local authorities.

Prince George's County Fire Department spokesman Mark Brady, said that two adults and one child in the church van were killed, as was the driver of the pickup truck. Six children and eight adults were transported to local hospitals, Brady said, adding that eight of the injured --four children and four adults-- were in critical condition.

Brady said police believe the pickup truck initially rear-ended a passenger vehicle before going several hundred feet further up a road, losing control and then crossing a double yellow center line into the path of the van. Once the pickup truck had crossed over the line, the van struck it on the right side and the truck caught fire, he told The Associated Press.

"The fire actually involved the pickup truck" and not the van, he said by phone. Some bystander photos posted on social media showed flames rising above the crash site not far from the van, which Brady said could hold 15 passengers and had front-end damage from the crash.

He said the investigation was just in preliminary stages and that authorities are seeking to reconstruct the accident in exacting detail.

Brady said the crash was one of the worst scenes he has worked in a 40-year career.  He said the adults in the van were mostly in their 20s and 30s and that the children ranged from 4 to 10 years old. He added late Sunday that authorities were not yet releasing the names or the identity of the church group and drivers involved while relatives were being notified.

He added the crash was so bad that firefighters went through a "critical incident" debriefing afterward. "They were met with by counselors to make sure everyone was ok after dealing with an incident involving so many people, so many injuries and fatalities," he said.

A police spokeswoman did not return a call seeking comment Sunday evening.

Donald Huff, who lives on the street where the accident took place, said he heard "a loud boom, just like a bomb," and then saw the flames.

"The fire just got bigger and bigger," he told The Associated Press by phone.

He said a couple of people ran out on the street with kitchen fire extinguishers "to try to get as close as they could, but it was a little too much."

He said that when the fire department arrived and brought the blaze under control, he could see them pulling bodies from the van afterward. White smoke billowed from the scene afterward.

A witness also told WTTG-TV that she heard the crash from her home, and when she ran out, she saw "just regular people running in and pulling people out of the van." She said she saw bystanders remove at least four children from the van.

Photos taken by people nearby appeared to show flames shooting into the air. The photos showed the van and the pickup truck had halted in what appeared to be the front yard of a single-family home. The extent of the fire and other damage to the vehicles involved wasn't immediately known.

A spokeswoman for MedStar Washington Hospital Center said Sunday night that some of those in the crash had been sent there, but she had no additional details.

Brady said the injured were divided up among several hospitals in the area because of the number of people hurt.

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The Associated Press contributed to this report.