Six people are dead after an accident caused a van to catch fire on a Georgia highway.

The Gwinnett County police and fire departments were dispatched to northbound Interstate 85 where it splits to Interstate 985 on Saturday just after 6:30 p.m. in response to reports of a vehicle that was on its side and engulfed in flames, authorities said.

Passersby tried to pull people out of the burning van and render aid, police said. Several lanes of both highways were shut down as a result of the crash.

Six people died at the scene, and several others were transported to local hospitals in the Atlanta area, police said. All occupants of the passenger van appear to be adults.

One bystander who suffered a minor injury declined transport to the hospital.

Another car may have been either directly or indirectly involved in the incident, investigators believe, based on witness statements.

Police are still trying to determine what caused the crash.

ABC News’ Ben Stein contributed to this report.