Rescue workers were trying to reach at least 15 miners trapped underground in a gold mine in northwestern Colombia after it suddenly flooded, a government emergency response unit said on Wednesday.
"Search and rescue operations are under way. Up to now we have 15 people reported trapped in the mine," the National Unit for Management of Risk and Disasters said in a statement, adding the total number of workers could turn out to be higher.
"A mine collapsed, apparently after flooding caused by the holes drilled to extract the mineral," said Luis Pineros of the emergency response agency UNGRD.
"We're in the middle of search and rescue operations," he said, adding that saying 50 rescue workers and medics were on the scene.
The mine is in Riosucio in Caldas province around 136 miles northwest of the capital, Bogota, and has been operating legally, the government's mining agency confirmed to Reuters.
Some of the miners are trapped at a depth of about 55 feet, others at about 33 feet, according to the police commander for the department of Caldas, Luis Duarte.
The National Mining Agency said local firefighters reported that gases in the deep, vertical tunnels had likely contributed to the cave-in.
Last week, Colombian authorities arrested nearly 60 people in raids targeting illegal mining operations used to finance the Revolutionary Armed Forces of Colombia (FARC), the armed group that has waged a five-decade war on the government.
Business has boomed over the past decade for Colombia's illegal miners as the price of gold has risen from less than $400 per ounce to almost $1,200.
Most of Colombia's annual gold production is produced by informal or illegal miners working in precarious conditions, leading to frequent accidents.
Last year alone, 87 mine accidents claimed the lives of 120 people, according to government figures. In 2010, 73 people were killed in an explosion at a legally operated coal mine in Antioquia province.
Al Jazeera with wire services