SUFFERN, NY (CBSNewYork) — Two people were killed in a multi-vehicle crash on the New York State Thruway in Suffern Friday morning.

It happened around 9:47 a.m. on the southbound side of the thruway near Exit 14B for Airmont Road.

Police said the crash involved one tractor-trailer, two box trucks and another vehicle.

The accident was caused when one of the box trucks, which had been traveling northbound, crossed the median and entered the southbound traffic lanes, police said.

“It was a head-on between two trucks: a box truck and a tractor-trailer,” said state police Lt. Lawrence Muller.

Lt. Muller said the truck was trying to pass slower traffic when the crash occurred, WCBS 880’s Levon Putney reported.

“And when he attempted to merge back into traffic from the right lane back into the middle lane, he lost control of the vehicle and he ended up going across the guide rail and struck a tractor-trailer that was traveling southbound,” he said.

The two people inside the box truck were killed, Putney reported. The driver of the tractor-trailer and the driver of another box truck were injured.

Following the crash, truck parts could be seen littering the roadway, CBS2’s Lou Young reported.

The box truck that bore the brunt of the crash was smashed in the front and laying on its side in the middle of the southbound lanes with mattresses spilling out onto the roadway.

Hours after the accident, all southbound lanes remained closed and traffic is being diverted at Exit 15 to Route 17 South.

This on a Friday, when traffic along this corridor is normally heavy. Most of it is now being diverted, Young reported.

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State police tried to turn southbound Thruway motorists around, but they ended up filtering onto local streets to try to get past the wreck, Young reported. The ripple effect lasted all afternoon.

“[Route] 17’s at a dead stop, so we got off,” said one driver.

“(Young: How long have you been stuck? Four hours!” said another driver.

“We’re going from Suffern to Spring Valley,” one driver said. “(Young: And how long is it taking you?) An hour and a half. (Young: You’re still in Suffern, you know?) Yeah.”

Thousands of motorists were caught in the traffic, but the frustration vanished once they saw the wreck.

One truck driver said he missed all of his appointments, but managed to be grateful.

“I was mad when I saw this because I was running late and I had a bad day,” Tony Rodriguez said. “But now, thinking about it, it’s just sad because a guy is dead. He’s not going to make it to his family.”

The identifies of the two who were killed have not been released, pending family notification.