Chinese officials say a deadly explosion at an Internet cafe in the country's southwest appears to have been caused by an illegal storage of chemicals in a next-door shop.

Saturday's blast at the Internet cafe in Kaili city in Guizhou province killed seven people, injured 37 others and damaged surrounding buildings. One of those killed was a woman who died Sunday of severe burns.

China's official Xinhua news agency says authorities have detained one person for illegal possession of hazardous chemicals in a shop next to the cafe. The chemicals included sodium nitrate and aluminum chloride. It is not clear what ignited them.

Xinhua says 45 people were in the Internet cafe when the blast happened, with only one escaping injury. It says police detained the boss and the manager of the licensed facility for questioning.

Some information for this report was provided by AP and AFP.