HUNTINGTON, Utah (CNN) -- Three rescue workers were killed and six others injured Thursday night during an apparent "seismic bump" while attempting to reach six miners trapped since an August 6 mine collapse, according to state and hospital officials.
Maria Lerma hugs her daughter Adilene as she waits to hear news about her husband.
The third death was confirmed by a Utah Department of Natural Resources spokeswoman.
All of the rescue workers in the mine at the time of the incident have been accounted for and removed, said Rich Kulczewski of the Mine Safety and Health Administration.
"An accident occurred during the rescue effort at the Crandall Canyon mine at 6:30 MDT," the Mine Safety and Health Administration said in a statement.
"At this time, it is believed the accident was caused by a 'bump,'" the statement said.
A seismic "bump" is an increase in seismic activity in the area.
At least six ambulances and two helicopters rushed to the site and transported the injured to hospitals. Medics inside at least one ambulance were seen doing chest compressions.
Castleview Hospital in Price, Utah, was expecting up to 11 injured, at least one in very serious condition, said hospital CEO Jeff Manley.
The families of the affected rescue workers had been notified, Manley said.
Of the six patients received at Castleview so far, one was released, one was sent by helicopter to University of Utah Hospital in Salt Lake City, three were being treated for injuries and one died as a result of his injuries, according to Manley.
The University of Utah Health Sciences Center in Salt Lake City told CNN it sent two helicopters to the site, about a 45-minute flight away.
The center is about 115 miles northwest of Huntington and is one of two trauma centers in Utah's capital city.
"We are in an emergency situation," Bob Murray, president and CEO of mine co-owner Murray Energy Group Corp., told CNN. Watch interview with an eyewitness to the chaos surrounding the accident »
Mine worker Donnie Leonard said he was preparing to leave the scene when he first heard yelling about miners being trapped in a new collapse.
"People were running everywhere," gathering stretchers and supplies, he told CNN. He described the scene as "very chaotic."
Earlier, officials said rescue efforts have been going disappointingly slow, despite some encouraging news.
Samples taken from the third hole bored into the mine found that the air had a 16.8 percent level of oxygen, Richard Stickler, head of the U.S. Mine Safety and Health Administration told reporters Thursday.
Murray said video taken from a camera lowered into the hole showed a large, open cavity.
"If the men did go to this area that is open, the air is there, the water is there; everything is there to sustain them indefinitely until we get to them," Murray said.
But he stressed that rescuers do not know if the miners were in that area.
Rescuers are still more than 1,000 feet from reaching the section where the men were believed to be working, Murray said.
Seismic movement Wednesday night loosened rubble that covered the "continuous miner" machine -- a powerful plow that chews up coal and shovels it into carts following behind -- halting work for a while, Murray said. Another shake delayed work later Thursday morning, he said.
"I'm so sorry, ladies and gentlemen, to tell these families that we're not making better progress underground," Murray said. "And it's strictly due to the fact that the mountain is still alive and the mountain is not allowing us to advance as rapidly as we would like to."
Rescuers planned to drill a fourth hole to try to find the miners, who've been trapped for 10 days in the central Utah coal mine. See photos of the rescue efforts »
Before Thursday night's collapse, Murray said it probably would take two days to drill the 1,586-foot-deep shaft.
On Wednesday, underground listening devices, called geophones, picked up a "series of spikes" over a five-minute period.
Rescuers said they didn't know what the sounds were, but they said they were encouraged.
Murray said the sensors have not picked up the noises again.
"Those sounds could have been anything, and we've said that from the beginning," Murray said Thursday.
Two earlier bore holes have yielded no signs of life, but they have shown there is survivable space and some breathable air, rescuers have said.
The six miners were trapped August 6, when the mine collapsed.
Murray maintains that an earthquake, not mining activity, caused the collapse. However, seismologists at the U.S. Geological Survey say there was no earthquake and the collapse registered as a 3.9-magnitude quake.
Friends and family have identified the trapped men as Louis Alonso Hernandez, 23; Manuel Sanchez, 41; Kerry Allred, 57; Carlos Payan, in his 20s; Brandon Phillips, 24; and Don Erickson, 50. See the miners' profiles » E-mail to a friend
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