According to a doctor who treated the wounded at Tora Bora:

A doctor who treated wounded al-Qaida fighters at Tora Bora in Afghanistan has confirmed Osama bin Laden was at the mountain stronghold as U.S. and Afghan forces attacked – and said the al-Qaida chieftain seemed concerned about only his own welfare.
Ayman Saeed Abdullah Batarfi, a doctor from Yemen, told a military panel at Guantanamo Bay that he carried out amputations with a knife and scissors in the caves of Tora Bora during the siege in late 2001 and had to abandon his patients several times when B-52 bombers flew overhead.
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“Most of all the total guns in the Tora Bora area was 16 Kalashnikovs and there are 200 people,” Batarfi told the Guantanamo military panel, which was weighing whether to release the detainee, in broken English. “He did not prepare himself for Tora Bora and to be frank he didn’t care about anyone but himself.
“He came for a day to visit the area and we talked to him and we wanted to leave this area. He said he didn’t know where to go himself and the second day he escaped and was gone.”