The driver who died in a crash Monday night in Flanders may have had a medical episode before his pickup truck struck three cars and then collided head-on with another pickup, police said.

Southampton Town police said investigators are awaiting the results of an autopsy to determine the cause of death of James Sager, 57, of Babylon.

The accident occurred on Flanders Road at about 8 p.m. Police said the crash scene spanned about a quarter-mile.

The pickup truck driven by Sager was traveling westbound in the eastbound lanes when it hit three vehicles, then struck the other pickup truck head-on, police spokeswoman Lt. Susan Ralph said. She said no one in the other vehicles was seriously injured.

She said a woman, who was the driver of the last vehicle struck, was airlifted to Stony Brook University Hospital, where she is in stable condition.

The identity of that driver was not released.

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After the accident, Flanders Road was closed for hours in both directions between Longneck Boulevard and Pleasure Drive.

It was not clear when the results of the autopsy would be released. Police said the investigation is continuing.

With Ellen Yan