Woods was there first from the annex to go to the mission, I think Doherty was later, part of the group of mixed US and Libyan forces sent from Tripoli to aid the mission who ran into an ambush on the way but who did finally get there to rescue 30 people.
Since anyone else -an in extremis force, etc, would have had to come from outside the country, they would need, as FR’s Travis McGee has said, “cross border authority” to go in armed. There is only one person who can grant or deny cross border authority, and that is the President of the United States.
Which is why the Obama admin is stalling, and why the people most concerned - Sec of state and Defense, and the pres himself, have left the country to go on wine tasting expeditions to Australia and to hug human rights activists in Burma.