Gunmen have taken students hostage and killed at least 14 people at a university in north-eastern Kenya, near the Somali border, aid workers and police say.
About 30 were wounded after gunmen stormed Garissa University College. Troops have surrounded the campus and are engaging the attackers.
Witnesses spoke of the gunmen firing indiscriminately and there are fears the casualty toll could rise.
Islamist al-Shabab militants from Somalia have regularly targeted Kenya.
Garissa and other border areas have often been attacked.
Exchange of fire
Some five masked gunmen are said to have stormed the university.
A policeman at the scene told Reuters news agency that some students had been taken hostage.
"We can't tell how many but they are many since the college was in session," the unnamed policeman is quoted as saying.
The Kenyan Red Cross said about 50 students had been "safely freed", but an unknown number were still being held, AFP news agency reports.
Security forces were now trying to flush out the gunmen, a police statement posted on Twitter said.
It urged people to stay away from the area. The statement did not confirm that hostages had been taken.
Two guards were confirmed killed at the main university gate, with two policemen and a student among the injured. But eyewitnesses spoke of many casualties inside the building.
The gunmen reportedly ordered students to lie down on the floor, but at least 27 are known to have escaped and are at a military facility.
"It was horrible, there was shooting everywhere," student Augustine Alanga told the BBC's Newsday programme.
He said it was "pathetic" that the university was only guarded by two police officers in such a volatile area.
Kenyan Red Cross spokeswoman Arnolda Shiundu said there were about 30 casualties, four of whom were critical.
Three people - two soldiers and a civilian - had been airlifted to the capital, Nairobi, she said.
The university opened in 2011 and is the only place of higher education in the region. It has some 900 students, mostly from other parts of Kenya.
Garissa, 150km from the border with Somalia, has a large population of Kenyan Somalis.
Al-Shabab, which is part of al-Qaeda, 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.