South Windsor, CT – South Windsor Police Sergeant Matthew Mainieri was vacationing in South Carolina when he was killed by a man who “sucker punched” him as he was trying to break up a fight, police said.

The incident occurred at approximately 12:30 a.m. on Sunday at Uncle Tito’s bar, the Georgetown County Sheriff’s Office said, according to WMBF.

When a fight broke out inside the bar, Sgt. Mainieri, 41, attempted to intervene, at which point he was “sucker punched” by 21-year-old Kelton Todd, the department said.

Sgt. Mainieri sustained massive head injuries in the assault. He was rushed to a local hospital, where he died at approximately 3 p.m.

"It is with profound sadness that the members of the South Windsor Police Department mourn the death of Sergeant Matthew Mainieri," South Windsor Deputy Chief Scott Custer in a statement on Sunday, according to WMBF. "Police Sergeant Matthew Mainieri #155 died this afternoon of injuries sustained in an off-duty incident in South Carolina last night while trying to break up a fight."

Todd was transported to the Georgetown County Detention Center and was initially charged with assault, WTIC reported.

Additional charges are expected, pending findings of the ongoing investigation, the sheriff’s office said.

Sgt. Mainieri, a 20-year veteran of the force, served as an officer, corporal, and sergeant during his time with the department, Chief Custer said.

He served in the Detective Division and Traffic Division, and was also a member of the Metro Traffic Services regional traffic unit.

Sgt. Mainieri was an accident reconstructionist, firearms instructor, and motorcycle instructor.

“He was…an outstanding instructor,” Chief Custer said.

Sgt. Mainieri was skilled at “explosive breaching,” and was a member of the department’s Regional Emergency Services Team, the chief added.

More recently, the sergeant had been working to help the agency establish a drone program to assist in locating suspects and missing individuals.

During his tenure with the department, Sgt. Mainieri received many commendations, including the Chief’s Award, the department Medal of Valor, and multiple certificates, Chief Custer said.

“This is the worst possible news one can imagine and we are totally heartbroken,” South Windsor Mayor Dr. M. Saud Anwar told WVIT. “As I think some of the people who are in our police departments, they’re never off-duty. They’re always there to help out and that’s exactly what he was doing.”

Sgt. Mainieri leaves behind his girlfriend, mother, sister, and many friends.

“We send our thoughts and prayers to his family and friends as well as his police family throughout Connecticut and beyond,” Chief Custer said. “We will be assisting his family during this difficult time.”

Our thoughts and prayers are with the family of South Windsor Police Sergeant Matthew Mainieri, both blood and blue. Thank you for your service.

Rest easy, hero. We’ll hold the line from here.