DALLAS (CBSDFW.COM) – Dallas police have launched an internal investigation into a chase that ended in a fiery explosion near residences Tuesday morning, sources tell CBS 11. Investigators are questioning whether the officers involved violated department policy by pursuing their suspects.

The charred dirt remains outside a family’s home where the suspects’ car caught fire. A Dallas police squad car was chasing what officers believed to be a stolen car. Both the police car and the suspects’ car were involved in separate crashes at the intersection of Marsh Lane and Townsend Drive.

A ball of fire erupted as video shows two teenage suspects being chased by police crash into a road sign.

“I heard the crash, and I looked out the window,” said Jamison Pendergrass. “The car was pretty engulfed.”

Several neighbors in the area told CBS 11 they heard the impact. Two recalled seeing the police car in pursuit with its lights flashing. However, none of the remembered hearing sirens, which is one possible violation of the police department policy regarding chases.

“I heard the little silver car flying down my street, and I would say probably 75 to 80 miles an hour,” said Mary Mock.

Mock said she watched the suspects’ vehicle run the stop sign and hit a black pickup truck. Moments later, the officers’ squad car entered the intersection where police said it collided with a white pickup truck.

“I looked over and saw the police officer had not moved yet, so I called 911 to tell them there was an officer down,” said Mock.

Police said the suspects, officers and three people from the other vehicles involved were hospitalized with non-life-threatening injuries, leaving some witnesses surprised no one was more seriously hurt.

Over the last decade, the Dallas Police Department has tried reducing injuries and deaths by limiting high-speed chases to those involving violent felony suspects. This is another policy, sources said, the pursuit appeared to violate.

Neighbors in the area defended the officers’ actions.

“You have to do what you can as safely as you can, but I don’t think they were wrong to pursue them,” said Pendergrass.

Sources said the officers’ dash cam shows their vehicle hit a speed of at last 80 miles per hour.