CHONGQING - A coal mine gas blast has left 13 people dead in Southwest China's Chongqing municipality, local authorities said Wednesday.

The accident took place at Fufa Coal Mine in Dashu Township of Fengjie county at about 1:10 pm Monday, when 16 miners were working underground, the Chongqing municipal government said in a statement.

Three miners were rescued. Nine were killed instantly and four others were later found dead, according to the statement.

Rescuers retrieved the bodies of four miners after two days of searching, bringing the death toll to 13, it said.

Six people in connection with the accident have been detained by police, it said.

The Fufa Coal Mine began operation in September 2008 with an annual output capacity of 40,000 tonnes.

Police and work safety authorities are further investigating the accident, the statement said.