ATTLEBORO - One person was thrown from his car and three other people were injured in a spectacular double-rollover accident on Interstate 95 early Saturday morning.

A 2001 Volkswagen Jetta and a 2002 BMW were both traveling south at a high rate of speed in the middle and left lanes, respectively, when they collided shortly before 2 a.m., sending the two cars careening into the woods on the right side of the highway between Newport Avenue and Washington Street (Route 1), according to state police Sgt. Michael Popovics.

The driver of the BMW was identified as Vannareth Sin, 24 of Lowell.

Adam Demers, 23, and Zachary Jacob, 19, both of Attleboro, were in the Volkswagen along with a third person who police are still trying to positively identify.

It was not clear Saturday night who was driving the vehicle. According to emergency personnel at the scene, the all four involved suffered serious injuries, with the driver of the Volkswagen being thrown from the vehicle.

"Everyone involved was seriously injured," said Attleboro Fire Capt. Tom Joubert. "One was possibly life-threatening; the other three suffered multi-trauma, but possibly, life-threatening" injuries.

Demers, Jacob and Sin were all treated and released from Rhode Island Hospital by Saturday night, Popovics said, while the fourth victim remained in the hospital overnight.

It took firefighters about 30 minutes to extricate a trapped victim from the Volkswagen, having to use chainsaws to cut trees around it.

"They probably went 100 feet along the woods and probably topped 10 or 20 trees," Joubert said. "There were some good-size pine trees."

There were marks about 20 feet in the air on some trees.

"It was a sight. They were going fast," Joubert said.

One of the cars motor and transmission landed about 30 feet away from the rest of the vehicle.

"They both rolled numerous times," Joubert said of the cars. "They both went into the woods. The other ended up hitting a tree and bouncing back out of the woods."

According to Joubert, Sin claimed several times that he had two passengers in his car, but authorities, using a state police tracking dog, were unable to find anyone. "We never found either," he said. "They may have left the scene, but I just don't see two people walking out."

All the injured were taken to Rhode Island Hospital, Providence, by two ambulances each from Attleboro and Pawtucket.

Both vehicles were totalled.

Firefighters were tied up at the scene for about three hours, Joubert said, and the state police closed two lanes of travel for some time while they investigated the wreck.

The cause of the accident remains under investigation by the state police, led by Trooper Jason Morse.

State police are asking anyone who may have witnessed the crash to call the Foxboro barracks at 508-543-8550.

STEPHEN PETERSON can be reached at 508-236-0377 or at speterson@thesunchronicle.com.