(CNN) A senior U.S. intelligence official emphatically denied that the CIA refused repeated requests from its officers on the ground in Benghazi, Libya, to assist the Americans under attack at the U.S.
mission there.

Just five days before the presidential election and in a rare briefing to reporters, the official Thursday offered almost a minute-by-minute account of what happened that night.

According to a Fox News report last Friday, citing an unnamed source, CIA officers working at an annex about a mile from the mission were told by officials in the CIA chain of command to "stand down"
after receiving a call from the mission asking for help.

"There were no orders to anybody to stand down in providing support," the senior intelligence official said, offering a passionate defense of the actions taken by the CIA officers on the ground during the
September 11 attack that killed Ambassador Christopher Stevens and three other Americans.

The official insisted the agency operators at the annex were in charge of their movements and the safety of those who were preparing to respond to the initial attack on the mission compound.

There was "no second guessing" their decisions, the official said.

According to a detailed timeline provided by the official, there was a roughly 25-minute gap between the time those officers received the initial call for help from the mission to the time when the
approximately half a dozen officers were able to get underway to assist.

During that time, according to the official, CIA officers at the annex location were loading weapons and equipment into their vehicles, while others were on the phone trying to get local "friendly"
militias with heavier weapons to help. The official said the officers responded "as quickly and as effectively as possible."

The team from the annex came under fire at the mission, the official said, but was able to gather all of the U.S. personnel at the mission except for the missing ambassador and headed back to the annex
where they again faced small arms fire for about 90 minutes before the attackers left.

The Fox report also suggested that the officers on the ground urgently asked for military backup, but that the CIA also denied those requests. The official said that reporting was wrong. The military, the
official said, provided drone surveillance and there were a couple of military officers as part of a CIA security team from Tripoli to assist.

That security team was delayed at the Benghazi airport and did not arrive at the annex until early morning, shortly before that facility came under a sudden and intense attack that lasted 11 minutes. Two
officers, Tyrone Woods and Glen Doherty, were killed by mortar fire.

The attack has become part of the political debate as the Obama administration has been harshly criticized by many Republicans for initially describing the incident as a spontaneous protest against an
anti-Islamic video on the web and evolved into an assault on the mission.

The senior intelligence official said there was a need to address this issue now because some of the media mischaracterizations of what was done that night is a disservice to the men who had to make
decisions under fire.

Here is the timeline of events, as provided by the senior intelligence official:

– Around 9:40 p.m. (local time) the annex receives the first call that the mission is under attack.

– Fewer than 25 minutes later, a security team leaves the annex for the mission.

– Over the next 25 minutes, the team members approach the compound, attempt to secure heavy weapons and make their way onto the compound in the face of enemy fire.

– At 11:11 p.m., the requested drone surveillance arrives over the mission compound.

– By 11:30 p.m., all U.S. personnel, except for Stevens, who is missing, depart the mission. The exiting vehicles come under fire.

– Over the next roughly 90 minutes, the annex receives sporadic small arms fire and rocket-propelled grenade rounds. The security team returns fire and the attackers disperse at approximately 1 a.m.

– At about the same time, a team of additional security personnel lands at the Benghazi airport and negotiates for transport into town. Upon learning the ambassador is missing and that the situation at
the annex has calmed, the team focuses on locating the ambassador and tries to obtain information on the security situation at the hospital.

– It's still predawn when the team at the airport finally manages to secure transportation and an armed escort. Having learned that Stevens is almost certainly dead and that the security situation at the
hospital is uncertain, the team heads to the annex to assist with the evacuation.

– They arrive with Libyan support at the annex at 5:15 a.m., just before the mortar rounds begin to hit the annex. The two security officers are killed when they take direct mortar fire as they engage the
enemy. That attack lasts only 11 minutes before dissipating.

– Less than an hour later, a heavily-armed Libyan military unit arrives to help evacuate the compound of all U.S. personnel.Intelligence Official Offers New Timeline For Benghazi Attack