BALTIMORE (AP) — An off-duty police officer who was getting a haircut shot and killed a man who burst into a Baltimore barber shop and fatally shot a barber, police said.

Police said they believe the same man was responsible for two earlier shootings, one of them fatal.

The Baltimore Sun reports that police are trying to determine a motive linking all three shootings.

Police said one victim was in critical condition after a shooting that occurred at about 2 p.m. Saturday following an argument. Another victim died from a shooting near the Greektown section of Baltimore.

The third and final shooting happened at about 3:15 p.m. at The Bladi Style barber shop in Baltimore’s Medford neighborhood. Police Commissioner Michael Harrison said the suspect “entered the barber shop, produced a handgun, fired it at one of the barbers who was working in the barber shop, striking that barber.”

Harrison said the off-duty Baltimore police sergeant was getting a haircut from another barber. The officer, who was armed and in plain clothes, responded quickly and fatally shot the man, Harrison said. The officer, who was not identified, was not injured.

Harrison said detectives have linked the barber shop shooting to the two earlier ones, but he declined to elaborate.

Police declined to identify the names of the victims pending notification of family members.