A Facebook page that sprung up shortly after the blast and quickly grew to tens of thousands of members listed condolences, prayers and outrage at mine safety.
"My father was a coal miner in WV in the 1930s," one poster wrote. "He told me of running out of a coal mine as fine silty dust trailed behind him. It appears mining is NO safer now than it was then!"
Massey Energy is one of the nation's largest coal producers, but has had a spotty safety record. The company paid out millions of dollars in fines last year alone after admitting to repeated safety violations.
Manchin said an investigation would come later.
"I don't know what happened," Manchin said. "We're going to find out and do everything in our power to never let this happen again."
Eddie Morris, a rescue task force member and third-generation miner who was at work in a mine more than an hour away raced to the scene after receiving messages that there had been an explosion at Upper Big Branch.
Whether any survivors come out alive, he said, "God has everything to do with it."
Officials had hoped some of those missing were able to reach airtight chambers containing enough food, water and oxygen to help them survive for four days, Kevin Stricklin of the Mine Safety and Health Administration told The Associated Press . But when rescue teams were able to access one of the two nearest chambers, they found it empty.
"It does not appear that any of the individuals made it to a rescue chamber," Stricklin said at a news conference. "The situation is dire."
Benny R. Willingham, 62, a miner who was five weeks away from retiring, was among those who died, his sister-in-law Sheila Prillaman, told the AP.
He had made plans to take his wife on a cruise to the Virgin Islands after retiring, Prillaman said.
She expressed her anger at Massey's handling of the situation, saying family members only learned of Willingham's death when they saw it on a list posted by the company, instead of being contacted by a representative.
Though the ever-present risk coal miners face every day is thrust into the spotlight anytime disaster strikes, Morris said miners just get up and go to work like everyone else.
"There's an inherent risk in there, but there's an inherent risk on the highway," Morris said. "I wouldn't do anything else."
The blast could be heard, and felt, for miles.
"Before you knew it, it was just like your ears stopped up, you couldn't hear," miner Steve Smith told ABC Radio. Smith felt the blast while working underground at another site about seven miles away.
"The next thing you know, you're just right in the middle of a tornado," Smith said. "We were able to make it since we weren't that far underground right there at that side of the mountain.
"We just hurried up and high-tailed it back to the outside," he said.
Machin admitted that the situation looks very bleak, but urged people to remain hopeful, pointing to the miracle rescue of Randal McCloy, who survived the 2006 Sago Mine, W.Va., explosion despite being trapped for more than 40 hours in a toxic environment.
"The families want closure," Manchin told reporters. "They want names ... these families are good people. Hard-working people. They understand the challenges. Right now I told them to do what they do best. Love each other and come together as a family."