BEIJING (AP) — A public bus caught fire Thursday in the southwestern Chinese city of Guiyang, killing five people and injuring 32, officials said.

The bus started to burn on a street shortly after noon, but the cause was not clear and was under investigation, local authorities said on an official microblog.

Guiyang police and fire officials said the fire was extinguished, but could not offer more details when reached over the phone.

Media reports said the bus was carrying about 50 passengers. Photos circulating online showed black smoke rising from the bus, which was burned to its frame.

Last year, a man set fire to a commuter bus in the southeastern port city of Xiamen, killing himself and 46 others. A deadly bus fire in 2009 killed 27 in the central city of Chengdu.