Authorities have doubled a reward to $10,000 as they search for the driver who struck and killed a volunteer firefighter outside a Somerville firehouse.

The Somerset County Prosecutor's Office says 75-year-old George Kavanaugh was hit and run over by a light-colored vehicle that backed out of the Lincoln Hose Company parking lot on March 6. He died at a hospital.

Authorities say a witness said the vehicle had been idling and parked in the area of the front bay firehouse door between 9:15 p.m. and 9:30 p.m.

Kavanaugh had been a volunteer member of the department for 50 years.

Anyone with information is asked to contact the Somerset County Crime Stoppers Tips Line at 888-577-8477.