<br/>A blast at a coalmine in Colombia has killed 16 miners and left about 70 trapped underground, officials say. The explosion happened late on Wednesday at the San Fernando mine in Amaga, Antioquia province. Officials say there is little likelihood of finding survivors as rescuers tried to get into the mine. <br/> <br/>The blast happened at 2200 local time on Wednesday when miners were changing shift, officials said. For that reason, the exact number of people inside the mine was unclear, they said. <br/> <br/>Rescuers were trying again to get inside the shaft on Thursday morning.<br/>