Seventeen military personnel were killed in an arsenal explosion in Hunan province on Tuesday afternoon, Xinhua News Agency reported on Wednesday.

The accident occurred at 4:45 pm in Hengyang as a group of soldiers was stocking ammunition, the report said, without giving further details.

The cause of the accident is under investigation, it added.

A publicity officer with the Hengyang police who refused to be named said no civilians were injured as the facility is in a rural area of the city.

The Beijing News quoted several witnesses as saying that the force from the explosion shattered windows of nearby homes and generated a mushroom cloud.

"This is a rare incident for the Chinese military since it had maintained an outstanding safety record for its arsenals," said Wang Ya'nan, a military analyst in Beijing.

Normally, ammunition will explode only after it is detonated by a fuse, which is separated from the shell when kept in an arsenal, Wang said.

"Shells and military explosives can withstand a certain level of impact," Wang said. "For example, TNT, one of the explosive materials commonly used by the military, can be detonated by an extremely strong impact, but it doesn't mean such impact will definitely cause a blast."

The incident is more likely the result of an operation gone wrong rather than a plotted action, he said.

Worldwide, nearly half of the armory accidents in the last five years have occurred in Russia. "It is because the Russian military has plenty of ammunition inherited from the former Soviet Union, which became volatile after a long period of storage," said Du Songtao, a military observer. "Lack of investment resulted in the Russian military's inability to properly maintain this old ammunition so accident often occurred."

Wang added: "Arsenal accidents are likely to cause terrible casualties, so the government and military must make sure that all safety hazards can be defused promptly and completely."

The most deadly arsenal accident in modern history occurred in Lagos, Nigeria, in January 2002 when a large stock of military high explosives at a storage facility was accidentally detonated. More than 2,000 people were killed in the blast and its aftermath.

zhaolei@chinadaily.com.cn