An explosion caused by accumulated gas in six adjoining coal mines in central Colombia has killed at least 11 workers and trapped 10 below ground, authorities said on Wednesday.
The explosion took place late on Tuesday in a rural area of Sutatausa, about 75 km (46 miles) north of Bogota.
"People are trapped between 700 and 900 meters," Cundinamarca provincial governor Nicola Garcia told journalists, adding more than 100 rescue workers had joined the search.
Two people had already been rescued and seven escaped unaided.
"We are making every effort with the government of Cundinamarca to rescue the people who are trapped alive," President Gustavo Petro said on Twitter. "A hug of solidarity for the victims and their families."
The mines were authorised to operate, the national mining agency said.
Serious accidents are common at open pit and subterranean coal and gold mines in Colombia, mostly at illegal or informal operations and those without proper safety measures.
The most serious recent accident occurred in June 2010, when 73 people were killed in a mine explosion the northwest.
(Reporting by Luis Jaime Acosta; Writing by Julia Symmes Cobb; Editing by Nick Macfie)
