A stun grenade, also known as a flash grenade or a flashbang, is a non-lethal weapon. The first devices like this were created in the 1960s at the order of the British Special Air Service

Special Air Service

Special Air Service or SAS is a corps of the British Army constituted on 31 May 1950. They are part of the United Kingdom Special Forces and have served as a model for the special forces of many other countries all over the world...

 as an incapacitant.

These grenades are used to temporally neutralize the combat effectiveness of enemies by usually disorienting their senses.
The flash of light momentarily activates all light sensitive cells in the eye, making vision impossible for approximately five seconds until the eye restores itself to its normal, unstimulated state. The loud blast produced by the grenade adds to its incapacitating properties by disturbing the fluid in the ear.

When detonated

Detonation

Detonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations are observed in both conventional solid and liquid explosives, as well as in reactive gases...

, the fuse/grenade body assembly remains intact. The body is a tube with holes along the sides that emit the light and sound of the explosion. This avoids shrapnel injury, but can still burn. The concussive blast of the detonation can injure and the heat created can ignite flammable materials such as fuel. The fires that occurred during the Iranian Embassy Siege

Iranian Embassy Siege

The Iranian Embassy siege took place from 30 April to 5 May 1980, after a group of six armed men stormed the Iranian embassy in South Kensington, London. The gunmen took 26 people hostage—mostly embassy staff, but several visitors and a police officer, who had been guarding the embassy, were also...

 in London were caused by stun grenades. The filler consists of about 4.5 grams of a pyrotechnic metal-oxidant mix of magnesium

Magnesium

Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...

 or aluminium

Aluminium

Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 and an oxidizer such as ammonium perchlorate

Ammonium perchlorate

Ammonium perchlorate is an inorganic compound with the formula NH4ClO4. It is the salt of perchloric acid and ammonia. It is a powerful oxidizer, which is why its main use is in solid propellants...

 or potassium perchlorate

Potassium perchlorate

Potassium perchlorate is the inorganic salt with the chemical formula KClO4. Like other perchlorates, this salt is a strong oxidizer and potentially reacts with many organic substances...

.

Lethality of stun grenades

Although stun grenades are often designed to be non-lethal, several deaths have been attributed to their use. These include:

• In May 2003, a woman named Alberta Spruill died from a heart attack after a police team detonated a stun grenade at her residence in Harlem
  Harlem
  Harlem is a neighborhood in the New York City borough of Manhattan, which since the 1920s has been a major African-American residential, cultural and business center. Originally a Dutch village, formally organized in 1658, it is named after the city of Haarlem in the Netherlands...
  
  , New York. Her family eventually won a $1.6 million civil suit against the city.

• In February 2011, a North Carolina SWAT
  SWAT
  A SWAT team is an elite tactical unit in various national law enforcement departments. They are trained to perform high-risk operations that fall outside of the abilities of regular officers...
  
  police officer was injured at his home when a stun grenade accidentally detonated while he was attempting to secure his equipment. He underwent emergency surgery but later died of his injuries.

External links

• FM 3-23.30 "Grenades and Pyrotechnic Signals". globalsecurity.org, 1 September 2000. Ch. 1, Sec. 10. "Stun Hand Grenades". Retrieved on 26 May 2011.