A Massachusetts man who burned over 60% of his body in a tractor-trailer accident on Route 287 North in Mahwah Tuesday night remained in critical condition Wednesday evening, Mahwah Police said.

Clarence J. Belton, 64, of Chicopee, Mass., likely fell asleep at the wheel of his truck, or suffered from a medical condition that caused him to veer off the road at about 10:35 p.m. Tuesday, Mahwah Lt. Philip Tangel, one of the officers who responded to the scene of the accident, told Patch Wednesday morning.

Belton’s tractor-trailer struck another tractor-trailer that was parked on the shoulder of the highway, drove through the guardrail and careened into the woods, he said.

“In doing so, he punctured the gas tanks in his truck, and the entire tractor-trailer was engulfed in flames, and the driver, himself was completely engulfed in flames,” Tangel said.

When police arrived to the scene, Belton had dragged himself out of the truck, and was lying on the ground next to it burning, he said. Tangel and responding officer Sgt. Rob Curtis used a fire extinguisher to put out the fire that police said had burned off all of Belton’s clothing and skin from the chest down.

“Over 60% of his body had third degree burns, from his chest down to his toes” Tangel said.

Belton was transported via Mahwah Ambulance to Hackensack University Medical Center where he was stabilized, and then transported to the Burn Center at Saint Barnabas Hospital in Livingston, police said. He remained in critical condition Wednesday morning.

The Mahwah Fire Department and Franklin Lakes Fire Department fought the blaze that completely destroyed the tractor-trailer, which was hauling milk cartons, and had spread to the trees surrounding the accident, Tangel said. The fire was out by Wednesday morning.

The driver of the parked truck, which was carrying new cars, suffered minor leg injuries, police said.

Dacnys Camejo, 29, of Miami, Fl., was transported via Mahwah Ambulance to Good Samaritan Hospital in Suffern, N.Y., police said.

New Jersey State Police are investigating the accident.

Route 287 remained closed for hours Tuesday night into Wednesday morning as authorities continued to clean up debris from the accident and subsequent fire.

Submit your questions or news tips to jessica.mazzola@patch.com. And, remember to sign up for Patch's daily newsletter, and get updates on Facebook and Twitter.