BEIJING - Chemicals illegally stored in an adjacent room caused the blast that destroyed an Internet cafe, leaving seven dead and 38 injured on Saturday night in Southwest China, local police said on Sunday.

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The illegally stored chemicals exploded at 11:05 pm in a room next door to Lianxun Internet Cafe in downtown Kaili city in Guizhou province.

Packs of hazardous high-concentration aluminum chloride and sodium nitrite had been stacked along a wall of an adjoining shop, which sold chemicals. Bottles labelled nitric acid and petroleum ether were also found at the site, said a spokesman with Kaili municipal government.

But it was not clear why the chemicals exploded, local police said.

Forty-five people were in the cafe when the explosion happened. Only one of them was not injured, according to a statement from Guizhou's public security department after an initial investigation on Sunday.

The death toll from the explosion rose to seven after a seriously injured woman died on Sunday afternoon.

The woman died of severe burns in a local hospital at around 4:30 pm, according to a statement from the Kaili municipal government.

On Sunday investigators were identifying the bodies of the dead, one of whom was a child.

The deadly blast ripped through the Internet cafe, which was located under a bridge, leaving it in rubble and its walls darkened, according to footage on China Central Television, the country's State broadcaster. All the people inside were trapped for some time.

The explosion sent horrified people in the Internet cafe rushing for the exit, the Xinhua News Agency reported.

Some saw their clothes catch fire and others were thrown to the ground and trampled upon, Xinhua reported.

Long Jiuke, 18, heard a very loud sound and was pushed down by a strong shock wave.

"I crawled outside after struggling to set myself free from under a collapsed desk," said Long, who was under treatment at a local hospital for burns to her face.

The blast was so powerful that the walls of a house 5 meters away from the Internet cafe were brought down, reported a local Web portal.

The windows of two nearby buildings were also shattered, with broken glass scattered over roads around the scene.

In addition to the patrons in the Internet cafe, some people living near the scene were also injured, Xinhua said.

Police have detained Wu Zhanzhi, owner of the chemical shop, for illegal possession of the chemicals. The Internet cafe's owner, Chen Chenggui, and manager, Xing Guangchang, were also being questioned by police, according to Xinhua.

Rescue work had been completed and eight of those who suffered burns were in a serious condition but with no danger to their lives, Pan Dingjie, a publicity official of Kaili, capital of the Qiandongnan Miao and Dong autonomous prefecture, told China Daily on Sunday afternoon.

The Internet cafe, with 140 computers, has been operating with a license for several years, police said.

A further investigation is under way.

On Sunday, the Ministry of Culture ordered a nationwide safety inspection of Internet cafes and other entertainment venues.

"Relevant departments and bureaus have been ordered to take immediate concrete measures and carry out nationwide safety inspections of cultural venues," the ministry said on its website.