Dallas Police Shooting Marks Deadliest Attack on Police Officers since Sept. 11, 2001The brutal shooting deaths of five police officers in Dallas Thursday night is one of the worst attacks on U.S. law enforcement in 100 years and marks a grim milestone — the deadliest night for police officers since the terrorist attacks on Sept. 11, 2001. Five police officers have already been confirmed dead after the ambush attack at an anti-police brutality protest, but that number could rise as six more officers are wounded, according to Dallas police. Statistics from the National Law Enforcement Officers Memorial Fund place the attack among the deadliest ever on U.S. police officers. Seventy-one officers were killed as a result of the terrorist attacks on Sept. 11, 2001, giving it the dubious designation as the worst ever. Milwaukee\n\nThe next deadliest attack on police occurred in the Midwestern city of Milwaukee, Wisconsin, in 1917, when a bomb exploded in a police station, killing nine Milwaukee police officers. The bombers were never found. Oklahoma City\n\nOther deadly attacks include the 1995 Oklahoma City bombing, in which eight federal officers were killed after Timothy McVeigh exploded a bomb outside the Alfred P. Murrah Federal Building, and a 1929 prison riot in the Colorado State Penitentiary that left eight corrections officers dead. Over an eight-day period between Dec. 31, 1972, and Jan. 7, 1973, a member of the Black Panthers, Mark Essex, went on a killing spree that left nine people dead, including five police officers. He was killed on Jan. 7 by police snipers. According to Memorial Fund statistics, 51 law enforcement officers have been killed in the line of duty during 2016. That number is down slightly from the same time during 2015, when 58 police officers were killed.