SOMERVILLE — Authorities, seeking the public's help in the hit-and-run death of retired Somerville firefighter George Kavanaugh, have increased their reward to $15,000 for anyone who provides information leading to the apprehension of the person involved.

Crime Stoppers of Somerset, which initially set the reward at $2,500 and raised it to $5,000 in mid-March, is now offering $10,000, Somerset County Prosecutor Geoffrey D. Soriano announced Wednesday.

That reward money is in addition to the $5,000 reward announced by Somerset Sheriff Frank J. Provenzano late last month.

Kavanaugh, 75, was fatally struck on March 6 in front of Somerville Fire Department Lincoln Hose Company No. 4's firehouse located at 34 Warren Street.

According to an eyewitness, a light-colored SUV had been "idling" and parked in the area of the front bay firehouse door minutes before backing up and striking the victim. Authorities have said they're looking for information leading to the identity of the owner and/or operator of that light-colored vehicle.

At approximately 9: 25 p.m., Kavanaugh, a life-long Somerville resident, was standing on the sidewalk directly in front of the firehouse awaiting a ride from his friend when he was struck, police have said.

George Riehman, 74, and Kavanaugh were leaving the firehouse, having stopped there to socialize after attending the viewing of another fallen veteran firefighter, Riehman has told NJ Advance Media.

Riehman, a fellow retired firefighter and Kavanaugh's best friend, said he had gone to get his car when he saw "a guy backed over George, rolled over him again and then sped off."

"I heard George yell so loud. It was the loudest yell I ever heard. If the driver of that car didn't see George, I know he heard him scream. I was in shock," Riehman said.

Riehman said he didn't get a good look at the driver but remembered the vehicle was a light-colored SUV.

Kavanaugh, who was transported to Robert Wood Johnson University Hospital-Somerset, where he died from his injuries, was a the chief of the Somerville Fire Department in 1985 and 1986. He served as a firefighter for 50 years, holding various posts within the company. He was also a life member of the state's Firemen's Association.

An Army veteran, he was a member of American Legion Post 12 in Somerville.

Authorities are asking anyone with information to contact the Somerset County Crime Stoppers Tips Line at 888-577-8477. Tips can also be submitted online. All anonymous Crime Stopper tips will be kept confidential.

Dave Hutchinson may be reached at dhutchinson@njadvancemedia.com.Follow him on Twitter @DHutch_SL. Find NJ.com on Facebook.