Masked gunmen from Somalia's Shebab Islamist group stormed a Kenyan university Thursday as students were sleeping, hurling grenades and shooting dead at least 15 people before taking Christians hostage.
Scores of others were wounded in the assault, still ongoing some 12 hours after the first grenades were used to blast open the gates of the university in the northeastern town of Garissa, near the lawless border with war-torn Somalia.
The Al-Qaeda-linked Shebab claimed the pre-dawn attack, the same insurgents who carried out the Westgate shopping mall massacre in Nairobi September 2013, when four gunmen slaughtered at least 67 people in a four-day bloodbath.
"We were woken up by sounds of gunfire... no one knew exactly what was going on, ladies were screaming and people were running for their lives," student Ungama John said.
Other students said they saw up to four masked gunmen. Shebab spokesman Sheikh Ali Mohamud Rage told AFP the gunmen had taken non-Muslims hostage, but gave no numbers.
"When our men arrived, they released the Muslims. We are holding others hostage," Rage said, describing those seized as Christians. "Our people are still there, they are fighting and their mission is to kill those who are against the Shebab," he said.
"Kenya is at war with Somalia," Rage said, referring to the thousands of Kenyan troops in Somalia as part of an African Union military mission. Gunfire could still be heard sporadically 12 hours after the attack began, as Kenya's interior ministry said the "attackers have been cornered in one hostel".
Soldiers with tanks were deployed around the campus. Interior Minister Joseph Nkaissery said 15 people had been killed, and that "one suspected terrorist" had been arrested attempting to flee.
Kenya's official National Disaster Operation Centre said a further 65 had been injured, many suffering from gunshot wounds.
The Kenya Red Cross, which is leading the medical response to the attack, said there were "an unknown number of student hostages" and that "50 students have been safely freed".
The town of Garissa is around 150 kilometres (90 miles) west of Somalia and has in the past been targeted by militants from the Shebab. Police chief Joseph Boinet said "the gunmen shot indiscriminately" after storming the compound.
The sprawling campus, on the outskirts of the garrison town, has both teaching areas as well as residential blocks. The university has several hundred students from different parts of Kenya. The number of teachers and students trapped inside the campus was unclear as gunfire and explosions were heard coming from the site.
"Police... engaged the gunmen in a fierce shootout, however the attackers retreated and gained entry into one of the hostels," Boinet said, adding that reinforcements had arrived and were "flushing out the gunmen."
Witness Ahmed Nur said he saw the bodies of two university guards, shot by the attackers. Kenya Red Cross, quoting local health officials, said that 30 people had been taken to hospital, "the majority" with gunshot wounds.
Kenya has been hit by a wave of grenade and gun attacks, often blamed on sympathisers of the Shebab and sometimes aimed at police targets, since the army crossed into southern Somalia in 2011 to attack Islamist bases.
A series of foreign travel warnings in response to the threat have crippled Kenya's economically important tourism industry. On Wednesday, just hours before the attack in Garissa began, President Uhuru Kenyatta said Kenya "is as safe as any country in the world".
On Thursday, he offered condolences to those killed, but said security forces had made the "appropriate deployment to the affected area". British High Commissioner Christian Turner condemned the "cowardly" attack, while US Ambassador Robert Godec called the killings "heinous".
Kenya's government has been under fire since the Westgate attack. In June and July last year Shebab gunmen killed close to 100 people in a series of attacks on the town of Mpeketoni and nearby villages.
In November, Shebab claimed responsibility for holding up a bus outside Mandera town, separating passengers according to religion and murdering 28 non-Muslims. Ten days later 36 non-Muslim quarry workers were also massacred in the area.