BOGOTA, June 5 (Xinhua) -- Seven miners have died after an explosion at a coal mine in Colombia's central department of Cundinamarca, local authorities confirmed Friday.

The blast occurred Thursday afternoon at a mine in the municipality of Sutatausa, local media reported. Preliminary information showed the explosion was caused by a buildup of gas underground.

Rescue teams were sent to the site shortly after the accident.

Cundinamarca Governor Jorge Emilio Rey Angel expressed condolences to the victims' families on social media and released the names of the miners killed.

He said Colombia's National Mining Agency will open a formal investigation to determine the exact cause of the accident.

Mining accidents are not uncommon in central Colombia, where some mines fail to fully comply with safety regulations. ■