(NBC NEWS) - At least 70 people were killed and 79 others injured Thursday after al Qaeda-linked gunmen stormed a college campus in Kenya and targeted Christians, according to the country's disaster operations center.
Masked attackers "shot indiscriminately" and "heavy gunfire and explosions" were heard during the standoff at Garissa University College that was still ongoing after 12 hours, authorities and eyewitnesses said. The Red Cross confirmed that an unknown number of students were being held hostage.
Kenyan Interior Ministry says via its Twitter account that two "terrorists" had been killed in "the ongoing security operation" at the college.
Al Shabab, an al Qaeda-linked terror group based in neighboring Somalia, claimed responsibility for the pre-dawn attack. Sheik Abdiasis Abu Musab, the group's military operations spokesman, said many Christians were being held by the militants. "We sorted people out and released the Muslims," he told Reuters.
A student whose high school is just across the street from Garissa University College told NBC News he was walking to school when he heard gunfire and explosions. The gunfire had been ongoing for more than 12 hours, said the 16-year-old, who is not being named by NBC News.
"You can still here it now," he said at 6 p.m. local time (11 a.m. ET). "There was a lull but now the shooting has intensified again in the last ten minutes."
Backing up what other eyewitnesses have said, the student told NBC news that his best friend, who is on the basketball team at the university, was allowed to leave by the attackers after proving he was a Muslim by reciting the Shahada.
Robert Godec, the U.S. ambassador to Kenya, condemned what he called a "heinous terrorist attack" by al Shabab.
Collins Wetangula, the vice chairman of the student union, said he was preparing to take a shower when he heard gunshots.
When the gunmen arrived at his dorm he could hear them opening doors and asking if the people who had hidden inside whether they were Muslims or Christians. "If you were a Christian, you were shot on the spot," Wetangula told The Associated Press. "With each blast of the gun I thought I was going to die."
He added: "We started running and bullets were whizzing past our heads and the soldiers told us to dive."
Aden Abubakar, 29, who works in construction in Garissa, told NBC News he had just finished praying when he heard gunshots and explosions from the university around 500 yards away. Abubakar said he saw students running from the university compound "helter skelter," some of them naked or partially naked as they had been sleeping when the violence erupted.
Authorities said the attackers were holed-up inside dorms after a lengthy gunbattle with security services. Officials said the town was "locked down."
Some 70 people had been killed and 79 injured in the incident, the NDOC said via its Twitter account. It also said that 500 people had been rescued from the college during the operation that it said was ongoing.
Local residents donated blood outside Garissa hospital in the shade of a tree.
The Interior Ministry said one "suspected terrorist" had been arrested trying to flee the scene of the siege. It also released a "wanted" poster featuring a $215,000 reward for a fugitive allegedly linked to the attack.
Red Cross Kenya spokeswoman Arnolda Shiundu told NBC News that 50 students had been "safely freed" from the college compound after the attackers struck.
According to Shiundu, the attack began at around 5 a.m. local time (10 p.m. Wednesday ET) with an explosion at the university's gate. The masked gunmen then forced their way into the compound and moved toward accommodation for female students, she added.
In a televised statement, Kenyan President Uhuru Kenyatta admitted that the country had "suffered unnecessarily due to shortage of security personnel." He said he had directed police chiefs to fast-track 10,000 pending officer recruits to report for duty immediately.
Al Shabab has carried out past attacks in Kenya. In 2013, it claimed responsibility for an assault on Nairobi's upscale Westgate Mall that left more than 60 dead.
Police statistics show that 312 people were killed in al Shabab attacks in Kenya from 2012 to 2014.
In February, al Shabab released a video calling for attacks on shopping malls in the U.S., Canada and the U.K.
Thursday's university attack comes three days after President Barack Obama announced he would visit the East African country in July. It also prompted the State Department to urge U.S. citizens in Kenya to "review their own personal security measures."