Five people are in custody following the al-Shabab attack in eastern Kenya on Thursday which left almost 150 people dead, officials say.
Some suspects were arrested while trying to flee to neighbouring Somalia, the internal security ministry said. One is said to be a security guard.
At least 148 people died when gunmen attacked Garissa university campus. Four of the gunmen were also killed.
Al-Shabab has since pledged a “long, gruesome war” against Kenya.
The militant group said its attacks were in retaliation for acts by Kenya’s security forces, who are part of the African Union’s mission in Somalia against al-Shabab.
In Garissa, a survivor has emerged from hiding more than two days after the assault was unleashed.
The 19-year-old girl was found unhurt in a cupboard on Saturday, but security officials had to bring in a teacher to convince her that it was safe to come out.
She told reporters that she drank body lotion when she felt hungry.
Four other people were found alive on the campus on Friday, including two suspects. One was said to be a Tanzanian national with no known links to the university.
While many of the survivors spoke to the media, little is known so far about those who were killed.
Their bodies have been flown to Nairobi for identification, as local mortuaries have been unable to cope, and many of the students killed came from other parts of the country.
Meanwhile the bodies of the four gunmen who died have been put on public display in Garissa.
There has been criticism in Garissa, which is 150km (100 miles) from the Somali border, at how the security services dealt with the attack.