A Mastic man was airlifted to Stony Brook University Hospital with serious injuries Thursday evening after, police said, his motorcycle was struck by a car whose driver failed to stop at an intersection in Calverton.

Riverhead Town police said the motorcyclist, identified as Charles R. Pitre, suffered “injuries to his lower extremities” when he was ejected from his 2009 Harley Davidson in the collision at the intersection of Manor Road and Twomey Avenue at 6:19 p.m.

The driver of the car, identified as Paul J. Mejia of Middle Island, remained at the scene, police said. Police said he was not injured.

Police said Mejia, driving a 2001 Toyota Camry, failed to stop at a stop sign on Twomey Road, colliding with Pitre’s motorcycle.

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Mejia was issued a traffic summons at the scene, police said.

Detectives are asking anyone who might have witnessed the crash to call them at 631-727-4500. All calls will remain confidential.