TAIPEI (Taiwan News) -- An unexploded American-made phosphorous bomb from WWII suddenly ignited on Tuesday afternoon (July 16) in a residential backyard New Taipei City.

At 5 p.m. on Tuesday afternoon a man discovered a rusty object had begun to burst into flames on a slope in his backyard near Huweipaotai Park (the remains of a fortress) on Zhongzheng Road in New Taipei City's Tamsui District, reported SETN. When the man realized it was an unexploded bomb, he immediately dialed 119.

When police arrived on the scene, they cordoned off an area of 90 meters around the bomb, evacuated 14 people living the area, and notified the Army bomb disposal unit. Specialists then extinguished the fire and removed the bomb from the scene by 9 p.m., before destroying it in a secure location.

Bomb before it began to emit smoke. (New Taipei Police Department photo)

According to the 56-year-old owner of the house surnamed Hu (胡), he had discovered the bomb in the past few days. SETN cited Tung Yueh-lung (董岳隆), a military officer at the scene, as saying that the unexploded ordnance had been probably been exposed by recent heavy rains and the subsequent high temperatures may have caused the WWII weapon to ignite.

Tung said that ordnance was white phosphorous bomb left over from WWII that was 90 centimeters in length and had a blast radius of 90 meters. The officer said that white phosphorous can spontaneously ignite when the ambient temperature reaches 20 to 30 degrees Celsius.

White phosphorous burns at a temperature near 2,760 degrees Celsius and was used extensively on both military and civilian targets in WWII. However, because it was considered an extremely barbaric weapon to use on civilians, its use against non-combatants was banned by the 1980 Convention on Certain Conventional Weapons Protocol III, which the U.S. signed in phases from 1995 to 2009, though the weapon has still found its way on the modern battlefield.

Bomb bursts into flames. (New Taipei Police Department photo)

The bomb found in New Taipei was likely dropped by an American bomber during a massive raid launched on greater Taipei during WWII. The raid, known as the Taihoku Air Raid, took place on May 31, 1945 and was part of the largest allied air raid on Japanese-occupied Taipei (then known as Taihoku) during WWII.

The raid consisted of 117 Consolidated B-24 Liberator heavy bombers from the U.S. Fifth Air Force and lasted from 10 a.m. until around 1 p.m. During the air raid, American bombers dropped approximately 3,800 bombs on military units and government facilities, and despite efforts to avoid civilian casualties, some civilian facilities were mistakenly struck.

Over 3,000 died as a result of the massive bombing raid, more than all the casualties from the previous raids in Taiwan combined. Tens of thousands were also displaced or became homeless. Despite being camouflaged, the Governor-General's Office, now known as the Presidential Office, suffered a direct hit, was rendered inoperable, and was not repaired until Nationalist forces came to Taiwan after the end of WWII.

Bomb squad carefully removes bomb. (New Taipei Police Department photo)