Five people have died following a pair of chain-reaction crashes on an Arizona highway on Thursday, officials say.
The first crash occurred around 3:30 a.m., while traffic was backed up due to a commercial truck fire on the eastbound side of Interstate 10 near Riggs Road in Chandler, according to a press release from the Arizona Department of Public Safety.
A semi-truck driver "failed to stop for congested traffic" near Wild Horse Pass Boulevard and rear-ended three other commercial trucks as a result, according to the officials. Only minor injuries were reported.
The second collision occurred about three hours later, when another semi-truck caused a six-car crash on I-10 by the Chandler Boulevard off-ramp, per Thursday's press release.
The truck driver rear-ended two passenger vehicles, sandwiching them between his vehicle and the back of a second commercial truck. The second truck was "thrust forward" and hit two other cars.
The cars wedged between the trucks "ignited and burst into flames" upon impact, DPS said. The fire eventually spread to both trucks.
All five people in the two passenger vehicles were killed, according to the department. The commercial driver who caused the crash suffered minor injuries, as did the other drivers involved in the collision.
The Maricopa County Office of the Medical Examiner has not released the victims' identities or official cause of death.
Never miss a story — sign up for PEOPLE's free weekly newsletter to get the biggest news of the week delivered to your inbox every Friday.
An investigation into the crash is ongoing. A spokesperson for DPS tells PEOPLE that no charges have been filed.
Troopers with Arizona Highway Patrol are looking into distracted driving "as a possible factor" in Thursday's deadly crash, according to Thursday's press release.
DPS Captain Keith Gephardt told KPNX that the driver of the truck in the second crash "did not appear to slow down much, if at all" before the collision.
Multiple people witnessed the second crash. A hotel worker told ABC affiliate KNXV-TV that the vehicles in the middle of the crash were "squished like an accordion."
"My first thought was, there's somebody in that car," they told the outlet.
Bystander Mark Schafer told NBC affiliate KPNX he "heard a loud bang" before he "saw the flames" erupting from the wreck.
"It was just a horrific, loud crash," he told the outlet, later adding, "I'm saying prayers for that family."