An internal U.N. report obtained Monday said bodyguards protecting parliamentarians fired indiscriminately into a crowd after a suicide bombing and that children bore "the brunt of the onslaught."
The report also said there was no evidence to show authorities had tried to identify those behind the shootings or bring them "to account for their crimes."
The United Nations mission in Afghanistan said the report is one of many conflicting views inside its organization and has not been officially endorsed.
The report by the U.N. Department of Safety and Security, obtained by The Associated Press, said it was not clear how many people died in the suicide bombing and how many died from subsequent gunfire after the Nov. 6 attack in Baghlan province.
The report said that as many as two-thirds of the 77 killed and more than 100 wounded were hit by gunfire; however, some estimates said the number of people shot was much lower.
"Regardless of what the exact breakdown of numbers may be, the fact remains that a number of armed men deliberately and indiscriminately fired into a crowd of unarmed civilians that posed no threat to them, causing multiple deaths and injuries," the report said.
Children bore 'brunt of the onslaught'
"It is believed that at least 100 rounds or more were fired into the crowd with a separate group of school children off to one side of the road bearing the brunt of the onslaught at close range," it said.
Though the U.N. report described the firing as deliberate, some witnesses told the AP that there was a blanket of smoke at the blast site so thick that they couldn't see who was shooting. Other witnesses, though, could see clearly enough to identify the gunmen as the lawmakers' bodyguards.
Adrian Edwards, the world body's spokesman in Afghanistan, confirmed the report's validity, but said it was one of several conflicting views inside the U.N. and that its findings had not been endorsed.
"What you are seeing at the moment represents part of the picture only. What hasn't been resolved is that there is widely diverging, contrary views on this, and until those have been resolved, there is no complete finding," he said.
According to Afghan authorities, most of the casualties were the result of the suicide attack. Interior Ministry spokesman Zemeri Bashary has said most of the victims were hit by ball bearings from the bomb, and not bullets.
The AP first reported Saturday that a preliminary U.N. report said as many as two-thirds of the 180 bombing casualties were from gunfire. The weekly report obtained Monday provided a more complete picture of the U.N. Department of Safety and Security's view.
It said that in the chaos following the suicide attack, bodyguards protecting the lawmakers opened fire into the crowd for several minutes.
"It has been confirmed that eight of the teachers in charge of this group of school children suffered multiple gunshot wounds, five of which died," it said.
The report said that further investigations "are being hampered by restrictions on witnesses and officials and that despite several arrests, there have not yet been any reports of who is responsible."
Among the dead were 61 students and five teachers, six members of parliament and five bodyguards. The deadliest previous suicide bombing in Afghanistan was in June, when 35 people were killed in a bomb attack on a police bus.
The attack happened as the lawmakers were being greeted by children on a visit to a sugar factory in Afghanistan's normally peaceful north.
Among the parliamentarians killed was Sayed Mustafa Kazimi, the chief spokesman of Afghanistan's only opposition group, the National Front. No group has claimed responsibility for the attack, and Afghan officials say they do not know who was behind the bombing. The Taliban has denied it was responsible. A government investigation is also under way.
Hundreds of children had crowded onto the tree-lined driveway leading to the New Baghlan Sugar Factory to greet visiting lawmakers when the blast went off. Witnesses and survivors describe bodyguards firing into the thick black smoke for up to five minutes after the attack.