Al-Shabaab claimed the slaughter was in retaliation for killings carried out by Kenyan troops fighting the group in Somalia.
"Kenyan cities will run red with blood," said al-Shabaab, according to the Site intelligence monitoring group. "No amount of precaution or safety measures will be able to guarantee your safety, thwart another attack or prevent another bloodbath."
The university in Garissa has shut indefinitely and schools and hospitals in the town, which is less than 160km from the porous border with Somalia, have boosted their security.
Authorities put the bodies of the attackers on public display, driving them through a crowd in an open-back pick-up in the hopes that someone might be able to identify them. Security forces also arrested five people suspected of a role in the attack. One was a Tanzanian found hiding with ammunition in the ceiling of the university; another was a college security guard who authorities believe may have helped the group get in.
"We suspect the Tanzanian was one of the combatants. He had ammunition with him when he was arrested," said Interior Ministry spokesman Mwenda Njoka. "We suspect the guard facilitated the entry [into the university]."
Three other men with links to the alleged mastermind of the attack, Mohamed Mohamud, were caught trying to slip across the border into Somalia, Njoka added.
Mohamud, also known as Dulyadin or Gamad, is a close friend of al-Shabaab's leader, Ahmed Omar Abu Ubeyd.
A Kenyan national, he was an engineer and teacher before he was radicalised. He once ran a madrassa in Garissa and is still thought to have family there.
The authorities have put a bounty of 20 million Kenyan shillings ($284,000) on his head.
Yesterday the Cairo-based top Sunni Muslim body Al-Azhar condemned the massacre. The militants spared Muslim students but taunted Christian and Jewish students before killing them, survivors said.
"Al-Azhar condemns the terrorist act committed by Somalia's Shabaab terrorist group in the Kenyan university of Garissa that left about 150 victims, and wounded tens of innocent students," the prestigious seat of Sunni Islamic learning said.
- Observer, AFP