• November 24, 1917 - Milwaukee, Wisconsin: Nine Officers killed by a bomb shortly after 7AM. The bomb was found planted in front of a church, and was brought to the station during morning roll call.

• April 15, 1872 - Tahlequah, Oklahoma: Eight US Deputy Mashalls shot and killed in the Going Snake Massacre. Six died on the spot, with two more succumbing to their injuries the next day.

• February 20, 1927 - Cape Cod, Massachusetts: Eight Coast Guardsmen patrolling for rum runners drowned in a 70mph gale.

• October 3, 1929 - Colorado State Penitentiary: Eight Colorado Corrections Officers killed in a prison riot.

• October 30, 1950 - Puerto Rico: Eight Puerto Rican Police killed in a nationalist uprising.

• April 19, 1995 - Oklahoma City, Oklahoma: Eight Federal Agents (four Secret Service Agents, two Customs Agents, 1 HUD Agent, and 1 DEA Agent) were killed in the Oklahoma City Bombing. A truck bomb parked in front of the Alfred P. Murrah Federal Building killed 168, ranging in age from 3 months to 73 years, including 6 military personnel and 19 children. The blast caused 759 casualties and did $652 million in damages.

Source: http://www.nleomf.org/facts/enforcement/deadliest.html