Last Thursday, Mark Wayne Moore, 21, of Hagerstown, also pleaded guilty to one count of assault, according to Washington County Assistant State's Attorney Duane Gigeous.
Moore's admitted role in the Aug. 15 incident was that he provided the weapon, but was not the shooter, Gigeous said.
He has been serving time in the Maryland Division of Correction on unrelated charges, court records said.
Additional charges of reckless endangerment, assault, assault with intent to murder, and conspiracy to commit murder were dropped in exchange for the pleas in both men's cases.
The shooting occurred just after 2:30 a.m. on Aug. 15 as police officers Christopher Kayser and Jeffrey Shifler were on routine patrol in the 400 block of North Potomac Street.
The officers were behind a car traveling south when it pulled to the west side of North Potomac Street, and Kayser saw a handgun being pointed from the passenger side of the car, police said.
Kayser heard about six shots being fired and saw the muzzle flash from the weapon, police said.
The car continued south on Potomac Street before stopping briefly at West Franklin Street, where two men got out of the back seat and fled on foot.
When police attempted to stop the car, it continued on West Franklin Street before striking a curb at the corner of West Franklin and High streets, where Bernhisel and Moore got out and fled on foot.
Moore was arrested later that day.
Bernhisel was arrested three days later.
A third man, Donnie "Buggsy" Caldwell, 18, of 1024B Noland Drive, was being held without bond while awaiting trial, court records said.
He faces charges of reckless endangerment, assault, assault with intent to murder and conspiracy to commit murder, according to Washington County Circuit Court files.
Police said Thursday that more arrests are expected. No one was injured in the shootings.