Joint law enforcement may be carried out with the assistance of other law enforcement agencies including two divisions of the Massachusetts State Police known as the Fourth (Boston)[4] and Fifth (Brighton)[5] barracks of Troop H which provide cooperation with the Cambridge Police Department.

[6] Patrol Officer Loughrey was stabbed to death on June 26, 1860, while attempting to arrest a suspect near what is known today as the Longfellow Bridge.

[8] Patrolman John Guthrie succumbed to injuries sustained five days earlier on December 26, 1926, when he was struck by a car while directing traffic.

[10] Patrolman Lawrence Gorman was shot and killed on September 3, 1960, while attempting to arrest two burglary suspects in Kendall Square.

He observed the two men breaking into a restaurant and tried to arrest them when they opened fire, mortally wounding him.

On May 14, 1961, the captured suspect, aided by his accomplice, escaped from the Middlesex County Jail along with another inmate.

[11] Patrol Officer Sean Collier was shot and killed on April 18, 2013, during a large-scale manhunt for suspects in the Boston Marathon bombing.

At approximately 10:30 pm one of the subjects approached Officer Collier as he sat in his patrol car and opened fire on him without warning, striking him several times.

The suspects then carjacked a vehicle and led police on a pursuit while throwing explosive devices at pursuing units.

The pursuit ended in Watertown, where one suspect was killed, and a Massachusetts Bay Transportation Authority police officer was shot and seriously wounded in a gun battle.