A silver sedan carrying five people flipped over on Route 48. in Peconic about 10:30 a.m. Thursday, according to bystanders.
It was not immediately clear if anyone suffered serious injuries in the accident.
“They swerved, the car flipped over and it went into the trees over there,” said witness Tony Anagnos of Peconic, pointing to the north side of the road. “I ran over there and saw some kid had some blood running down his face.”
He said the accident drew dozens of people and about 30 vehicles, including fire trucks, ambulances and police cars.
The Southold Police Department and the Southold Fire Department have not yet released information on the accident.
Mr. Anagnos, 27, who lives on Route 48, said the car was upside-down until it was cleared away at around 11 a.m. A portion of one eastbound lane and one westbound lane was closed for approximately 30 minutes, he said.