The governor of the US state of West Virginia has ordered that all coal production be halted following more deaths in the industry.
West Virginia mines have suffered a spate of fatal accidents
Governor Joe Manchin told companies not to "mine another lump of coal" until full safety checks had been made.
Two miners were killed in separate accidents on Wednesday.
Twelve miners died in an explosion last month that drew US Senate criticism over safety. Two more workers died in a fire at another mine three weeks later.
Mr Manchin said on Wednesday: "We're going to check for unsafe conditions and we're going to correct any unsafe conditions before we mine another lump of coal."
Last week US senators strongly criticised mining officials over the deaths of the 12 miners in the explosion at the Sago mine on 2 January.
The senators accused officials of failing to comply with their own safety regulations.
Senator Robert C Byrd, chairman of the hearing, said the deaths had been "entirely preventable".
The criticism was rejected by the acting head of the government agency responsible for mine safety.
Last week, West Virginia legislators passed a series of measures aimed at improving mine safety.
The proposals include a rapid response system and updated tracking devices.