A powerful blast at a prefabricated house in northwestern China on Monday killed at least seven people and injured 94, state news agency Xinhua said.

 

The explosion, whose cause was as yet unknown, occurred in the early afternoon in the town of Xinmin in Shaanxi province, damaging dozens of buildings including the local hospital, Xinhua said.

 

Four of the injured were in intensive care, it said.

 

Pictures carried by state media showed rescuers digging through the rubble of low rise buildings.

 

Some online news sites quoted residents as saying the blast could have been caused by illegally stored explosives.

 

China has a bad safety record, with previous blasts blamed on poorly stored chemicals or industrial explosives which are easy to get hold of due to their use in China's booming coal mining sector.

 

A series of powerful explosions last year at a chemicals warehouse in the northern city of Tianjin killed 165.

 

There have also been cases of people deliberately setting off blasts to settle local grievances such as land disputes.