RAPID CITY - The South Dakota Highway Patrol has released additional information about a Wednesday afternoon car accident that sent four teenagers and one adult to Rapid City Regional Hospital.

Sean Watson, 17, of Box Elder, was in critical condition in the intensive care unit of Regional Hospital on Thursday, according to a news release issued by the Highway Patrol.

Watson was driving his Chevrolet Cavalier eastbound on I-90 near Exit 61 in a two-lane construction zone when he crossed the center line and struck a Chevrolet Blazer driven by 58-year-old John Simien of Box Elder, according to the Highway Patrol.

Simien remains in fair condition at Regional Hospital.

Watson's three passengers were also injured in the crash. The front-seat passenger, 17-year-old Box Elder resident Lisa Moran, was also in critical condition Thursday, according to the Highway Patrol news release.

The two back-seat passengers, 17-year-old Christopher Schrader of Box Elder and 17-year-old Jacob McNabb of Rapid City, were in either fair or serious condition, the release said.

Watson, Moran and McNabb all had to be extricated from the vehicle. Schrader was ejected during the crash.

Authorities are still investigating the cause of the crash. Alcohol is not believed to be a factor.

No further updates were available by late Thursday afternoon.