May 7, 2010 -- Survivors of last week's massive oil rig explosion have told ABC News that alarms meant to warn them of an imminent blast never sounded, and oil industry experts now agree that a critical failsafe needed to prevent the blast and the subsequent spill didn't work.
They were two crucial safeguards that failed during the chain reaction that left 11 workers on the Deepwater Horizon dead and led to what some now believe could be the worst oil rig disaster in U.S. history.
"It was chaos," survivor Dewayne Martinez told ABC News. "Nothing went as planned, like it was supposed to."
Martinez and survivor Micah Sandell described the grotesque scene that followed the first concussion on the rig, when a huge plume of gas vapor belched from the well and encircled the Deepwater Horizon, and a second, larger burst, when that gas cloud ignited.
"It was people screaming and hollerin," Sandell said. "I never seen nothing like that. Never."
The first sign of trouble came when workers on the rig started to inject seawater into the well to replace a plug of mud that had been holding back the gas and oil. One of the valves on a massive safety device called a "blowout preventer" should have been closed, but was open, according to Eric Smith, associate director of the Tulane Energy Institute, who has been following developments out in the Gulf. That change in pressure would have launched the contents of the well pipe - first the seawater and mud, then the gas - up towards the surface.
"As the bubble made its way to us, it would get bigger and bigger and accelerate rapidly," Smith said. "First thing that would happen would be a water spout. It would have been raining salt water."
Martinez and Sandell said water and mud rose 300 feet into the air.
"I'm sure they tried to hit the switches," Smith said, referring to an emergency valve on the blowout preventer that clamps down on the pipe. "But it would have been too late."
By then, any spark in contact with the cloud of gas would - and did - turn deadly.
Officials from Transocean, the company that owns the rig and leases it to BP, told ABC News they would not speculate as to whether the alarms sounded, or if they did not, why.
Tony Buzbee, the lawyer now representing the two oil rig workers in a lawsuit against BP and Transocean, said he hopes to get those answers.
"It either tells you that the alarms failed or that somebody muted the alarm because alarms are so common out in the oil patch that sometimes as a matter of course, they mute alarms," he said.
The oil industry has long had confidence in its series of fail-safes meant to prevent a catastrophe. A key element in the system is one mammoth piece of equipment - the blowout preventer, or BOP. It's a 50-foot, 900,000 pound contraption that sits on the sea bed a mile underwater. It houses more than half-a-dozen hydraulic valves designed to shut off any leaks of oil or gas.
But documents obtained by ABC News show the industry has been well aware for years of significant problems with blowout preventers.
A Transocean official, presenting his findings at an industry conference in 2003, wrote: "Poor BOP reliability is a common and very costly issue confronting all offshore drilling contractors."
ABC News sent questions to BP about the alarm system and the blowout preventers, but BP did not respond. Transocean officials said Thursday they believe it is too soon to know why the blow out preventers failed.
But members of Congress said this week they plan to investigate what went wrong with the blowout preventer beneath the Deepwater Horizon, and determine whether the thousands of other rigs that dot the American coastline pose a continuing risk.
"We saw that this device didn't work. And there were three different backup systems, each one of them didn't work. And now we're suffering the consequences," said Sen. Bill Nelson, a Florida Democrat.
"The notion that these are a fail-safe mechanism, we're finding out that they're not as safe as people were led to believe," said Sen. Maria Cantwell, a Washington Democrat. The men who worked on Transocean's Deepwater Horizon say there were told this could never happen.
"They always tell us that we have safety devices and warnings and they got ways of shutting it in," Micah Sandell told ABC News." And it don't seem like they had nothing."