Seven of those injured were in serious condition late Saturday, Cauca provincial Gov. Juan Jose Chaux said in a statement.
Chaux said the search for survivors at the mine, located near the town of Suarez, 220 miles southwest of Bogota, was suspended Saturday evening because of darkness and bad weather, which made the open pit mine unsafe.
It was unclear how many people were missing, but earlier police officer Jose Delgado had told The Associated Press that about 50 people may have been in the mine the time of the landslide.
Images broadcast by RCN news showed the mine as a pit about 25 feet deep and 160 feet in diameter. Rescuers waded waist-deep through the mire, and heavy machinery also worked to remove the mud.
Local residents had begun digging in the mine after it was reported that gold had been found underground, Delgado said by telephone from the scene. He added that many of them appeared to have little experience in tunneling or mining, and that there was no registry or count of how many people entered the mine.
The governor said in the statement that the Suarez mayor had ordered the mine closed, but "the people went in despite being warned" it was dangerous. The site was owned by mining company Agromineros, it said.
Rich in resources, but with limited government presence across much of the country, Colombia is home to many such makeshift mines, particularly in zones where gold or emeralds have been found.
With little to no oversight, mining accidents are a frequent occurrence in this Andean country.
In February a mine explosion killed 32 people. The same month another accident killed 8 more miners.