Police say that a blown semi truck tire is behind the deadly head-on crash between a big rig and a bus in New Mexico on Thursday.

The accident happened on the afternoon of August 30th in Albuquerque, New Mexico.

According to New Mexico State Police, the semitruck was hauling produce east on Interstate 40 near Thoreau when it suddenly blew a tire, sending the rig veering across the median and into oncoming westbound traffic, where it collided head-on with a Greyhound bus heading from Albuquerque to Phoenix, Arizona, busting open the front of the bus and ripping open the trailer, strewing produce and debris everywhere.

Of the 49 bus passengers, 9 were transported to a nearby hospital for their injuries and 7 were killed. The truck driver also sustained injuries in the crash but is expected to make a full recovery. The health conditions of the injured passengers taken to the hospital have not been released, reported CBS News.

“It was horrible,” said witness Marc Gonzales.

“There was [sic] people trying to climb out of the windows of the bus … bystanders trying to help people getting ladders out of their truck to get to windows of Greyhound bus to assist…. When we went by the overturned semi, everything in the trailer was out on the road. It was a disaster. … You could tell people were in distress; screams were coming from the bus.”

A passing truck driver, Santos Soto III, filmed the aftermath of the wreck on his cell phone and says that the entire scene was devastating.

“I saw people sobbing on the side of the road as bystanders tried to comfort them… I was really traumatized myself, because I’ve been driving about two years and I had never seen anything like that before,” Soto said.

“I’m a pretty strong person and I broke down and cried for at least 30 minutes.”

The incident is still under investigation as official work to confirm that the blown tire was the cause of the wreckage.

“We are fully cooperating with local authorities and will also complete an investigation of our own,” Greyhound spokeswoman Crystal Booker said in a statement.

“It was an awe-inspiring terrible scene,” added Eric Huff, another witness to the crash.