Five people were injured when two cars collided on Barnes Road Wednesday afternoon. State police said three people were taken by medical helicopter to Boston hospitals, and a 21-year-old New Hampshire woman was in the hospital Thursday afternoon with life-threatening injuries.

According to state police, a preliminary investigation by state troopers from the Oak Bluffs barracks indicates that a red 2012 Jeep Wrangler with four occupants from New Hampshire and a black 2009 Volkswagen Tiguan driven by a 19-year-old Cambridge man collided near the airport Mobil station just after 2 p.m. Wednesday. The Jeep, traveling southbound on the road, apparently pulled to the right side of the road and then turned to the left into a U-turn. The Volkswagen, which was traveling behind the Jeep, came up on the left side of the Jeep, broadsiding it during the U-turn, state police said. The collision caused the Jeep to roll over and the Tiguan to veer off the road.

Heather LaFlamme, 21, of Berlin, N.H. was ejected from the Jeep’s backseat, state police said. She was taken to Brigham and Women’s Hospital in Boston with life-threatening injuries and remained in critical condition as of Thursday afternoon, according to state police.

The Jeep’s other backseat passenger, Seth Jones, 26, of Dummer, N.H., was admitted to Beth Israel Hospital in Boston with serious injuries.

The Jeep’s front seat passenger, Margaret Jones, 51, of Dummer, N.H., was also admitted to Beth Israel Hospital with serious injuries.

The Jeep’s driver, Thomas C. Jones, 51, was transported to Martha’s Vineyard Hospital with serious injuries, state police said. The Tiguan’s driver, Benjamin T. Johnson, 19, was released after being taken to the Martha’s Vineyard hospital for evaluation.

State police said an investigation is continuing to determine if criminal charges are warranted. Troopers are looking into whether the speed of the Tiguan was a contributing factor, and whether the right-side placement of the Jeep’s steering wheel affected the driver’s vision while taking the U-turn, police said.

The State Police Collision Analysis and Reconstruction team were transported to the Island by the State Police Air Wing on Wednesday. Investigators are interviewing witnesses and examining evidence to determine the sequence of events and potential causes of the accident, state police said, and no determinations have been made.

Troopers from the Oak Bluffs state police barracks and the Edgartown police are being assisted in the investigation by troopers from the State Police Crime Scene Services and the Cape and Islands detective unit.

Access to Barnes Road was blocked at both ends, from the blinker light to West Tisbury Road, for more than five hours on Wednesday. The town of Edgartown sent out an automated text alert asking drivers to avoid the area as they made their way to Edgartown for the 5 p.m. Fourth of July parade. The road was reopened to all traffic at 7:08 p.m.