The death toll in an attack by gunmen on a Kenyan university campus near the border with Somalia has risen to 15, - a police officer at the scene said. 

"I have counted 15 dead bodies being taken off the campus by a Red Cross ambulance, and that includes two of our officers who were also killed,"- the officer informed.

"We are finding it difficult to access the area, because some of the attackers are on top of a building and fire at us whenever we try to gain entry."

Somali Islamist group Al Shebaab has claimed responsibility for the attack, claiming they are holding Christian hostages inside.