At least five people were killed and seven injured in a coal mine accident in southwest China's Yunnan Province Tuesday, the local authorities said Wednesday.

A statement from the emergency response office of the Yunnan provincial government late Wednesday described the event only as a "gas accident."

It said the accident occurred at about 7 p.m. Tuesday in Shilin, a county administered by Kunming City, the provincial capital.

The government of Shilin said in a notice that a number of villagers from neighboring Luxi County, in Honghe Ethnic Hani and Yi Autonomous Prefecture, were illegally working in the mine when the accident occurred.

One of the injured, a woman, was in critical situation, doctors said.

Officials with the local public security and work safety supervision authorities are investigating the cause of the accident.