PROVIDENCE, R.I. — A fundraiser for a deceased Providence police officer turned ugly early Saturday when an off-duty Rhode Island state trooper allegedly punched a Providence police sergeant in the face at the police union hall.

The trooper, Edward J. Stenovitch, 41, was charged late Monday afternoon with one count of simple assault and battery, a misdemeanor. He was arraigned before a bail commissioner at Providence police headquarters and released on his own recognizance.

Detectives from the Providence police and state police investigated the case.

Providence Deputy Police Chief Paul J. Kennedy said that the “unprovoked attack,” on Sgt. Bernard “Teddy” Gannon, who was also off duty, left him with a broken nose and a laceration that required medical treatment at Roger Williams Hospital.

“This investigation revealed that this was an unprovoked attack of a Providence police officer,” Kennedy said. “He was not even in a conversation with this guy. He never saw it coming.”

Both officers are from police families. Stenovitch’s father, Edward Stenovitch, is a retired state trooper, while Gannon’s father, Bernard E. Gannon, retired as Providence police chief and is now the police chief in Burrillville. Teddy Gannon’s brother, Danny, is a Providence police lieutenant.

Hundreds of police officers from city, state and local departments gathered Friday night at the Providence Fraternal Order of Police, Lodge No. 3, at 40 Sheridan St., off Manton Avenue. They each paid $20 to raise money for Gladys Rocchio, the widow of Providence Patrolman Peter A. Rocchio.

Rocchio, 52, of North Providence, died on June 6 from injuries he sustained in an off-duty car crash in the city’s Mount Pleasant neighborhood.

It’s not unusual for the fundraisers to raise $10,000 or more for the families of deceased police officers.

The Providence police said that there were about 15 to 20 police officers inside the union hall when Stenovitch allegedly punched Gannon once in the face.

State police Maj. Elwood M. Johnson Jr., who heads the state police Professional Standards Unit, said that Stenovitch has been placed on paid administrative leave pending the results of an internal investigation.

He has been a state trooper for 15 years and he was most recently assigned to the Lincoln barracks.

Johnson would not confirm nor deny reports that several Providence police officers may have retaliated against Stenovitch.

“Certainly, the investigation is not done,” he said. “The whole thing is very disheartening.”

bmalinow@projo.com

Correction: Providence Police Sgt. Gannon's full name was incorrect in an earlier version of this report.