WASHINGTON - As thousands of gallons of oil continued to spew from a damaged well in the Gulf of Mexico, grim-faced industry executives came under withering attack Tuesday on Capitol Hill from senators who accused them of a "cascade of failures" and of trying to shift blame to each other.

In back-to-back hearings, senators accused BP, which owns the well, of misrepresenting blow-out preventers placed atop wells as fail-safe and of telling federal regulators that the drilling would have "no adverse impacts" to the environment.

"We can't have a world where people say one thing before they get a permit and then just act like they never said it," Sen. Barbara Boxer, D-Calif., told Lamar McKay, chairman and president of BP America. "You said we won't have a problem."

"We obviously did not expect a situation like this," McKay said.

The BP executive also told senators that the company was determined "to do all we humanly can to stop the leak, contain the spill, and to minimize the damage suffered by the environment and the people of the Gulf Coast."

But he said that Transocean Ltd., owner and operator of drilling rig, had "responsibility for the safety of drilling operations."

Steve Newman, Transocean's president and CEO, seemed to point a finger at yet another contractor, Halliburton. Although the investigation of the cause continues, he told the senators, "there was a sudden, catastrophic failure of the cement, the casing, or both."

An executive with Halliburton, which did the cementing, said it was operating under BP's plan. Halliburton's work was done "in accordance with accepted industry practice" and BP's plans, said Tim Probert, president of the company's global business lines.

"Halliburton is confident that the cementing work ... was completed in accordance with the requirements of the well construction plan," he said.

At a later hearing lead by Boxer, he blamed Transocean's blow-out preventer, saying had it "functioned properly this tragedy wouldn't have taken place." But Transocean's Newman said the blow-out preventers "were clearly not the root cause of the explosion" on April 20.

'One of my worst nightmares'

The back-and-forth drew the ire of several senators -- one of whom accused the executives of doing a "Texas two-step" to avoid liability -- as well as two lawmakers considered industry allies.

"I hear one message, and the message is: 'Don't blame me,' " said Sen. John Barrasso, R-Wyo. "Well, shifting this blame does not get us very far."

Sen. Lisa Murkowski of Alaska, the energy committee's top Republican, said: "I would suggest to all three of you that we are in this together."

Sen. Ben Cardin, D-Md., grilled McKay about representations that the blow-out preventers were designed never to fail when, he said, they have failed more than a dozen times.

"Obviously, this is an unprecedented accident," McKay said.

Lawmakers opposed to wider offshore drilling said they were sadly vindicated. "The bottom line is: If you drill in the ocean, an oil spill cannot be a surprise," Sen. Frank Lautenberg, D-N.J., said. And Sen. Bill Nelson, D-Fla., said, "One of my worst nightmares might be coming true."

Meanwhile, in Kenner, La., a hearing by the Minerals Management Service and the Coast Guard explored the immediate aftermath of the blast. Witnesses described in dramatic detail some of the early efforts to rescue rig workers and the dogged search for the 11 men who were presumed killed. "What you are looking for in these circumstances is about the size of a volleyball: a person's head," Coast Guard search and rescue specialist Kevin Robb said of trying to find survivors in the water.

Alwin Landry was the captain of the Bankston, a supply vessel alongside the Horizon drilling rig. He said he was in the bridge when drilling mud from the Horizon began to spew on to the back of his vessel, coming down "like black rain." He saw three men jump into the Gulf. The Bankston was credited with recovering or taking aboard all 115 survivors.

'It supposedly could not spill'

On Capitol Hill, the two hearings were the first to look into the incident. The executives will again testify Wednesday, and sessions are planned for next week.

The venue for the morning hearing, before the Senate Energy and Natural Resources Committee, had once been the setting for an investigation into the sinking of the Titanic, a fact that did not escape notice. "At that time we had a ship supposedly so technologically advanced that it could not sink," said Sen. Robert Menendez, D-N.J. "And here we have a rig that the industry has told us so many times is so technologically advanced it supposedly could not spill."

A handful of drilling opponents held up signs, "Spill Baby Spill" and "BP -- Bad People."

The hearings are expected to lead to legislation that will increase industry's liability for spills, a measure Sen. Amy Klobuchar, D-Minn., supports. A bill would raise the limit to $10 billion, from $75 million.

The climate was much hotter before Senate Environment and Public Works Committee, of which Klobuchar is a member. There, Lautenberg told the executives: "Each one of you must feel terrible torment."

Staff writer Kevin Diaz, the Washington Post, the Los Angeles Times and Associated Press contributed to this report.