State police said speed was a factor in a single-car accident that seriously injured two Vineyard men Sunday morning.

Police responded to the accident about 1:30 a.m. According to state police, a driver failed to negotiate a curve on the Oak Bluffs side of the big bridge, and the vehicle skidded into the dunes and rolled at least once. The occupants, John (Ethan) Leite, 27, of Oak Bluffs, and Nathan Belain, 26, of West Tisbury, were both injured and transported to the Martha’s Vineyard Hospital. They were then flown by MedFlight to Massachusetts General Hospital in Boston.

“Definitely speeding, that was a factor,” said Trooper David Parent, who investigated the accident. Mr. Parent said he expects to issue citations for speeding and reckless driving when the investigation is complete.

According to a spokesman at MGH, Mr. Leite remained in serious condition Tuesday morning, while Mr. Belain’s condition had been upgraded to good.

In an unrelated call, on Saturday evening at about 11:30 p.m., Chilmark police responded to an accident on Middle Road. Police first responded to a report of a man injured on Middle Road near Beetlebung Corner. There they found Kevin Boreri, 54, of Chilmark, bleeding from the face. According to the police report, Mr. Boreri admitted to police he had been drinking. He said he had not been driving but told police he lost control of his vehicle, according to the report. Mr. Boreri was transported by ambulance to the Martha’s Vineyard Hospital for treatment.

Police later located a vehicle registered to Mr. Boreri near Henry Hough Lane. The vehicle, a GMC Yukon struck three guard rail posts, two road signs and three trees before coming to rest down an embankment about 20 feet off the roadway.

Police cited Mr. Boreri on charges of driving under the influence of alcohol, second offense, negligent driving, leaving the scene of an accident, and a marked lanes violation.