A deluge gun, fire monitor, master stream, water cannon, or deck gun is an aimable controllable high-capacity water jet used for manual firefighting or automatic fire protection systems. Fire monitors are often designed to accommodate foam which has been injected in the upstream piping. Fire monitors are often fitted to fire boats and on top of large firetrucks for use in manual fire fighting efforts. Fire monitors are also used in fixed fire protection systems to protect high hazards, such as aviation hangars and helicopter landing pads. Most apparatus-mounted fire monitors can be directed by a single firefighter, compared to a standard fire hose which normally requires several. Fire Monitors can also be automatically positioned for fixed systems. They can pump up to, and sometimes over, 2,000 US gallons (7,600 L) per minute.

Deluge guns are also available in portable designs so a firefighter can set up the gun to apply water to a blaze then leave it in place so the firefighter is free for other tasks. Facilities with highly flammable material such as oil refineries may have permanently installed deluge guns for use in the event of a fire.

Daniel James "Dan" White (September 2, 1946 – October 21, 1985) was a San Francisco supervisor who assassinated San Francisco Mayor George Moscone and Supervisor Harvey Milk, on Monday, November 27, 1978, at City Hall. In a controversial verdict that led to the coining of the legal slang "Twinkie defense," White was convicted of manslaughter rather than murder in the deaths of Milk and Moscone. Less than two years after serving five of a seven year prison sentence, White returned to San Francisco and committed suicide. San Francisco Weekly has referred to White as "perhaps the most hated man in San Francisco's history."

Daniel James White was born in Long Beach, California, the second of nine children. He was raised by working class parents in a Roman Catholic household in the Visitacion Valley neighborhood of San Francisco. He attended Riordan High School until he was expelled in his junior year. He went on to attend Woodrow Wilson High School where he was valedictorian of his class.

White enlisted in the United States Army in June 1965. He was a staff sergeant in the 101st Airborne Division in the Vietnam War from 1969 to 1970. White had been honorably discharged in 1971.