Rescue crews have freed 20 freelance gold miners in northern Nicaragua, more than 24 hours after a mine collapsed and buried them underground, officials said Saturday. 

Authorities said they believe four more remain trapped in the El Comal gold and silver mine and the status of those miners is unclear. One miner said he saw an avalanche of mud and rock moving toward them and that at least four miners were crushed by it.  

"They are coming out little by little, it's a slow process but we want to make sure they can get out safely," Interior Vice Minister Carlos Najar Najar told state television.

The trapped miners were heard screaming for help by fellow workers who then used a tunnel to direct rescue teams.