Nairobi ( CNN ) An elite police commando unit waited hours for transport from Nairobi , Kenya , to Garissa , where Al-Shabaab terrorists had taken over a university on April 2 , according to one of the commandos who participated in the response operation . The commando asked not to be identified for fear of reprisals and because he was not authorized to speak . Al-Shabaab slaughtered 147 people at the school . Of the fatalities , 142 were students at the university , and the rest were security forces and campus security . At 7:00 a.m. local time , the response team was told to assemble for a mission to Garissa , the police commando told CNN . At 8:00 a.m. , he said , the team was told there were no police aircraft available to take them . A reserve team was then sent by road , while the main commando team waited in Nairobi for air transport , he said . Once told aircraft would be available , it took the commando team nearly two hours to travel the roughly 22 miles ( 35 kilometers ) to the airport because of the heavy traffic , the commando source said . But Kenya 's Police Air Wing Chief Col. Rogers Mbithi denied that his unit caused any delay in the response to the university attack . Mbithi told CNN two fixed wing aircraft were ready and waiting for the commandos 45 minutes before the police commandos were ready to depart around 12:30 p.m. local time . Government names Kenya attack mastermind . Mbithi conceded that one of the two aircraft ultimately used to transport the commandos to Garissa left Nairobi at 7:30 a.m. to fly to Mombasa on a scheduled flight , hours after the Garissa terror attack began . That plane picked up the chief 's daughter-in-law and two children , and returned to Nairobi at its scheduled time of 11:39 a.m. , Mbithi said . The first aircraft carrying police commandos eventually departed for Garissa at 12:30 p.m. , followed by a second aircraft about 10 minutes later , Mbithi said . Inside college dorm 's scene of slaughter . After arriving in Garissa by plane , the commando team rehearsed the assault on the university compound for about two-and-a-half hours , the commando source told CNN . The police assault to retake the university compound began around 5 p.m. and lasted about 15 minutes . One commando was killed in the assault . All four Al-Shabaab attackers were killed . Another law enforcement source told CNN that by 7:00 a.m. the Al-Shabaab terrorists had already killed most of the students , saying : `` It was never a hostage situation . '' The problems plaguing Kenya 's security efforts . Other Kenyan officials have previously defended the response to the university attack . Manoah Esipisu , a spokesman for Kenya 's President and deputy president , told CNN last week that in emergency situations there is always criticism regarding whether governments reacted as fast as they could have or should have . `` With the benefit of hindsight , you can always say things could have been done better , '' he said . Kenyan authorities saved a lot of students and `` got the job done , '' he said . Foreign Minister Amina Mohamed told CNN the response was sufficient and denied reports that it was the elite rapid response team alone that brought an end to the situation . `` We have a military garrison in Garissa , and the work began immediately after the attack was reported and continued for a number of hours until we were able to rescue 663 students of the 800 students that had been taken hostage by these terrorists . So the response was adequate , '' she said . Lillian Leposo reported in Nairobi . Lonzo Cook reported in Atlanta . CNN 's Jethro Mullen also contributed to this report .
Commando says air transport was delayed for hours as Garissa forces slaughtered students . On April 2 , 147 were killed at a university in Garissa , Kenya , most were students .