The man believed to have shot the officer was released from prison in August, authorities said.
Thomas Johnson III was wounded in the shootout Wednesday night. He was being held at Strong Memorial Hospital.
The police officer who was mortally wounded had not been identified Thursday morning. Police Chief Michael Ciminelli said he "made the ultimate sacrifice protecting the people of Rochester."
The officer was the first member of the Rochester Police Department to die in the line of duty since 1959, Ciminelli said.
Mayor Lovely Warren joined the chief for a news conference shortly after midnight at Rochester General Hospital.
"A family has lost a loved one, RPD lost a family member and Rochester lost someone who put his life on the line for us everyday," she said.
Police said the gunfire began at about 9:30 p.m. Wednesday when officers attempted to make an arrest. Ciminelli said a bystander was also wounded in the shootout and is expected to survive.
Johnson most recently spent a year in jail for violating parole. He served a three-year sentence for attempted robbery and a year for criminal trespass.
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