Washington - Minutes after Greg Hicks learned that the perimeter of the U.S. mission in Benghazi had been breached by men with guns, he punched a cell phone number to reach Ambassador J. Christopher Stevens, his immediate boss, who was at the scene.

"Greg, we're under attack," Stevens told Hicks, the deputy chief of the mission, Hicks testified to Congress Wednesday.

Then the connection was lost. Hicks never spoke to his boss again. Stevens died soon afterward, as the Benghazi mission went up in flames around him.

Members of the House Oversight and Government Reform Committee were universal in their praise of the gripping, soft-spoken, minute-by-minute account they heard Wednesday from Hicks, the first public testimony from a government official who was on the ground in Libya during the assault that killed four Americans in September.

Hicks for the first time explained that Stevens had traveled to Benghazi at a delicate time - the anniversary of the Sept. 11 attacks - for a mundane, bureaucratic reason. The State Department wanted to shift money from Iraq to the Benghazi mission to make it permanent, and Stevens needed to complete some paperwork by a deadline.

"Timing for this decision was important," Hicks said. "Chris needed to report before Sept. 30, the end of the fiscal year, on the physical and the political and security environment in Benghazi to support an action memo to convert Benghazi from a temporary facility to a permanent facility."

After the attack, the mission was evacuated, and it has not been reopened.

Hicks and two other State Department witnesses shed little new light on the key questions at issue in the hearing: whether there was anything more the U.S. military could have done to thwart the attack and whether the Obama administration intentionally misled the American people when officials initially said the attacks stemmed from a protest.

An independent review board has concluded that neither charge is true, but the Republican-controlled House is pressing on with investigations, with particular interest in the role of former Secretary of State Hillary Rodham Clinton, who may run for president in 2016.

Hicks testified that he received a phone call in Tripoli, Libya, from Clinton about 2 a.m. during the crisis. "Secretary of State Clinton called me, along - and along with her senior staff, were all on the phone. And she asked me what was going on. And I briefed her on developments," Hicks said.

Partisan politics loomed large over Wednesday's proceedings. Some House members have compared Benghazi to Watergate and to the 1980s sale of arms to Iran and diversion of the profits to Nicaraguan guerrillas.

The committee chairman, Rep. Darrell Issa, R-Calif., complained that the administration and Democrats on the committee have not supported his efforts to have questions answered.

The ranking Democrat, Rep. Elijah E. Cummings of Maryland, accused the Republican chairman of politicizing his inquiry.

Cummings challenged Issa's recent statements that the military could have done more to respond to the attacks. He noted that top military officials, including Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, have said there was no feasible military option that could have been carried out in time.

A State Department Accountability Review Board concluded that the U.S. response "was timely and appropriate, but there simply was not enough time for armed U.S. military assets to have made a difference." It found "no evidence of any undue delays in decision-making or denial of support from Washington or from the military combatant commanders."

"Chairman Issa has accused the administration of intentionally withholding military assets which could have helped saved lives on the night of the attacks, I say, for political reasons," Cummings said.

Issa did not respond but moved to opening statements of his witnesses, whom he called "whistle-blowers."

Hicks argued that fighter aircraft flying low overhead could have thwarted a mortar attack that killed two CIA contractors hours after the initial assault ended. But he acknowledged that he was not in a position to refute Dempsey and other top officials who said the planes could not have gotten there in time.

The Benghazi attack began about 9:40 p.m. Sept. 11, when a group of heavily armed men, accompanied by a mob, swarmed, shot at and set fire to the lightly defended diplomatic mission. Stevens and communications specialist Sean Smith were killed, and the mission was overrun.

More than six hours later, after the mission had been evacuated, assailants fired mortar rounds at the roof of a nearby CIA compound, killing CIA security contractors Glen Doherty and Tyrone Woods.

U.S. intelligence officials have said that although Islamic extremists were present, there is no evidence that al-Qaida ordered or planned the assaults.

Hicks said he was disgusted when he heard U.S. Ambassador to the United Nations Susan Rice say on television Sept. 16 that the attacks stemmed from a protest over an anti-Islamic video. There was no protest, Hicks said.

James Clapper, the director of national intelligence, has said the notion of a protest came from intelligence reporting that proved to be wrong.

After the initial attack, an eight-person rescue team organized by the CIA - a team that included Doherty - chartered a Libyan plane and flew from Tripoli to Benghazi. The team ultimately made its way to the CIA annex, where Doherty joined Woods in a firing position on the roof.