WASHINGTON U.S. officials are striking back at allegations they failed to respond quickly or efficiently against the deadly attack on the U.S. Consulate in Benghazi, Libya, detailing for the first time a broad CIA rescue effort.

Senior U.S. intelligence officials said Thursday that CIA security officers went to the aid of State Department staff less than 25 minutes after they got the first call for help from the consulate, which was less than a mile from a CIA annex.

The detailed timeline provides the first in-depth look at how deeply the CIA was involved in the rescue attempt, and it comes amid persistent questions about whether the Obama administration responded as quickly and effectively as it could to the siege.

The attack on the 11th anniversary of 9/11 by what is now suspected to be a group of al Qaeda-linked militants killed U.S. Ambassador 동인천출장안마 Chris Stevens and three other Americans in a protracted battle over the course of eight hours.

It’s believed two of the victims – Navy SEALs Tyrone Woods and Glen Doherty – died in a mortar attack some six or seven hours after the U.S. Mission was first overrun by a terrorist mob that burned buildings and used AK-47 rifles, bombs and mortars.

More in U.S. compound attack in Benghazi

U.S. officials described the timeline in a clear effort to rebut recent news reports that said the CIA told its personnel to “stand down” rather than go to the consulate to help repel the attackers.

The intelligence officials told reporters Thursday that when the CIA annex received a call about the assault, about a half dozen members of a CIA security team tried to get heavy weapons and other assistance from the Libyans. But when the Libyans failed to respond, the security team, which routinely carries small arms, went ahead with the rescue attempt. At no point was the team told to wait, the officials said.

Instead, they said the often outmanned and outgunned team members made all the key decisions on the ground, with no second-guessing from senior officials monitoring the situation from afar.

The officials spoke on condition of anonymity because they were not authorized to provide intelligence information publicly.

In the first days after the attack, various administration officials linked the Benghazi incident to the simultaneous protests around the Muslim world over an American-made film that ridiculed Islam’s Prophet Muhammad. Only later did they publicly attribute it to militants, possibly linked to al Qaeda, and acknowledged it was distinct from the film protests. The changing explanations have led to suspicions that the administration didn’t want to acknowledge a terror attack on U.S. personnel so close to the Nov. 6 election, a charge President Obama has strongly denied.

The circumstances of the attack, including the intelligence and security situation there, will be the subject of a Senate Intelligence Committee closed hearing on Nov. 15, with additional hearings to follow.

Information shared with CBS News from top counterterrorism sources in the government and military reveal keen frustration over the U.S. response on Sept. 11,

CBS News’ Sharyl Attkisson has been told that during the Sept. 11 attack on the U.S. Mission in Benghazi, the Obama Administration did not convene its top interagency counterterrorism resource: the Counterterrorism Security Group, (CSG).

“The CSG is the one group that’s supposed to know what resources every agency has. They know of multiple options and have the ability to coordinate counterterrorism assets across all the agencies,” a high-ranking government official told CBS News. “They were not allowed to do their job. They were not called upon.”

On Thursday, intelligence officials said they had early information that the attackers had ties to al Qaeda-linked groups but did not make it public immediately because it was based on classified intelligence. And they said the early public comments about the attack and its genesis were cautious and limited, as they routinely are in such incidents.

They added that while intelligence officials indicated early on that extremists were involved in the assault, only later were officials able to confirm that the attack was not generated by a protest over the film.

The officials’ description Thursday of the attack provided details about a second CIA security team in Tripoli that quickly chartered a plane and flew to Benghazi but got stuck at the airport. By then, however, the first team had gotten the State Department staff out of the consulate and back to the CIA annex.