GARISSA, Kenya — The Islamic extremists who slaughtered 147 people at a college in Kenya as they shouted “God is great” appeared to have planned extensively, even targeting a site where Christians had gone to pray, survivors said Friday.

Police on Friday were at the campus of Garissa University College, taking fingerprints from the bodies of the four assailants and of the students and security officials who died, for thorough identification purposes. The northeastern Kenyan town lacks the facilities to store all the bodies.

In Nairobi, Kenya’s capital, family members were lining up at a morgue where about 20 bodies had already been airlifted from Garissa, victims of the worst attack in Kenya since the 1998 bombing of the U.S. Embassy by al-Qaida which killed more than 200 people. Screaming and crying relatives of the victims were assisted by Kenyan Red Cross staffers, who tried to console them.

One of the first things that the al-Shabab gunmen did when they assaulted the campus early Thursday, survivor Helen Titus said, was to head for a lecture hall where Christians were in early morning prayer. Al-Shabab is a Somalia-based extremist group with ties to al-Qaida.

“They investigated our area. They knew everything,” Helen Titus told The Associated Press at a hospital in Garissa where she was being treated for a bullet wound to the wrist. Officials said 79 people were wounded.

Titus, a 21-year-old English literature student, said she covered her face and hair with the blood of classmates and lay still at one point during al-Shabab’s deadliest attack on Kenyan soil in hopes the Islamic extremist gunmen would think she was dead.

The gunmen also told students hiding in dormitories to come out, assuring them that they would not be killed, said Titus, who wore a patient’s gown as she sat on a bench in the hospital yard.

“We just wondered whether to come out or not,” she said. Many students did, whereupon the gunmen started shooting men, saying they would not kill “ladies,” Titus said. But they also shot women and targeted Christians, said Titus, who is a Christian.