BOGOTA, Colombia (AP) — A powerful explosion tore through a series of five coal mines interconnected by tunnels and ventilation systems in a rural area of central Colombia, killing at least 11 people and leaving 10 others missing, the government said Wednesday.

Nine other miners who got out of the complex after the blast were taken for medical examinations, and three were still being treated Wednesday evening, officials said.

President Gustavo Petro said on his Twitter account that rescuers were making every effort to reach the missing miners.

The blast, which was attributed to a build-up of methane gas, happened Tuesday night in Sutatausa, a municipality in Cundinamarca department about 75 miles (45 miles) from the capital, Bogota.

Álvaro Farfán, captain of the Cundinamarca fire department, told local media the explosion affected five mines interconnected by tunnels, generating a “chain" blast with a wide impact.

Petro said 11 miners had been confirmed dead. Energy and Mines Minister Irene Vélez said 10 people were unaccounted for.

Six bodies had been recovered by searchers, while five others had been sighted, said Javier Pava, director of the state-run National Unit for Disaster Risk Management.

Explosions and cave-ins are common in Colombia's coal mines.