Explosions and heavy gunfire continues to rock Garissa University College near the border with Somalia, Aljazeera reported citing local media.
It is expected that they have taken hostages inside the complex after raiding the university.
Two policemen and a student have been injured and rushed to hospital, and Kenyan defence forces are said to have arrived at the scene, media reported.
It is not clear who is responsible for the attack, but Somali al-Shabab militants have frequently targeted Kenya in the past few years.
Al-Shabab has carried out a number of attacks in Kenya since 2011, when Kenyan troops were sent to Somalia to help fight the militant group there.
The deadliest attack targeted the Westgate shopping centre in Nairobi in September 2013, when 67 people were killed. Al-Shabab is fighting to create an Islamic state in Somalia and is banned as a terrorist group by both the US and the UK.