ACTON (CBS) — A 75-year-old woman has died hours after she was found unconscious but breathing on Revolutionary Road in Acton, officials confirm.

Police say a 911 call came in for a woman down near 24 Revolutionary Road around 8:05 on Tuesday morning.

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Investigators at the scene of where a woman was hit by a car in Acton (WBZ-TV)

The woman was reportedly walking her dog when she was hit by the back of a car, officials believe.

She was airlifted to Mass General Hospital but passed away around 10:30 a.m., said police.

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Police remain on scene hours after a woman was hit by a car on Revolutionary Road in Acton (WBZ-TV)

“The type of vehicle was identified and we have located the vehicle and are currently speaking to the operant of the vehicle,” said Acton Police Lt. Ed Lawton.

Police are continuing to investigate what happened.

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No charges have been made at this time.