(CNN) — Latest developments:
•12:09 p.m.: Seventy people were killed and 79 others were wounded in the Al-Shabaab terror attack on Garissa University College in Kenya, the Kenya National Disaster Operation Center said Thursday. More than 500 students have been rescued, the center added. The school has 815 students. All staff has been accounted for, officials said.
Islamist gunmen burst into a Kenyan university before dawn Thursday, shooting students and taking hostages in a terror attack that left 70 dead, Kenyan officials said.
Two attackers were killed in the ongoing security operation, and one was arrested, authorities said.
More than 500 of the 815 students are accounted for at Garissa University College, the Kenya National Disaster Operation Center said. Staff members are accounted for as well.
The Somalia-based Al-Shabaab militant group claimed responsibility for the assault.
“This is a moment for everyone throughout the country to be vigilant as we continue to confront and defeat our enemies,” Kenyan President Uhuru Kenyatta said.
The attackers cornered a building in which 360 students live, but some of the students escaped, Interior Minister Joseph Nkaissery said.
Witness: Gunmen shot non-Muslims
Joel Ayora, who was on the campus and witnessed the attack, said gunmen burst into a Christian service. Taking hostages from the service, they then “proceeded to the hostels, shooting anybody they came across except their fellows, the Muslims.”
The attackers separated students by religion, allowing Muslims to leave and keeping an unknown number of Christians hostage, Agence France-Presse reported.
“We were sleeping when we heard a loud explosion that was followed by gunshots and everyone started running for safety,” student Japhet Mwala said.
“There are those who were not able to leave the hostels where the gunmen headed and started firing. I am lucky to be alive because I jumped through the fence with other students.”
Eventually, as many as 50 students were freed, and at least 65 people were hospitalized from the attack, the Kenyan Red Cross said.
Nine hours after the attack began, heavy gunfire and explosions continued, said Dennis Okari of CNN affiliate NTV.
Okari said he was told to take cover as hundreds of students fled, some crawling.
Kenyan forces cleared three of four dormitories and had cornered the militants in the last one, the Interior Ministry said.
Photo of wanted man released
The ministry posted a “Most Wanted” notice for a man in connection with the attack. The notice offers a reward of 20 million Kenyan shillings, which is about $215,000. The name listed is Mohamed Mohamud.
The post does not say what role the man may have played in the attack, if any.
It includes the words “Kaa Chonjo,” which means to be on the lookout.
President: Kenya suffering from police shortage
Garissa is about 145 kilometers (90 miles) from the border with Somalia. Al-Shabaab militants have often launched attacks inside Kenya ever since the Kenyan government sent troops across the border to fight the group.
Kenyatta called on the inspector-general of police “to take urgent steps” to ensure that 10,000 recruits whose enrollment is pending “promptly report for training at the Kenya Police College, Kiganjo. I take full responsibility for this directive. We have suffered unnecessarily due to shortage of security personnel. Kenya badly needs additional officers, and I will not keep the nation waiting.”
Waking up to terror
The gunshots started going off “like fireworks” around 5 a.m. at the time of the morning prayers, witness Milka Ndung’u told NTV. She and others escaped to a field, but gunshots followed them.
Augustine Alanga told CNN he woke up to the sound of gunfire and described students running around, seeking safety.
Assailants forced their way onto the campus by shooting at guards at the front gates, Kenya National Police said.
From there, attackers moved into a nearby girls’ hostel, the Red Cross said.
It’s not clear how many gunmen were on campus.
“We don’t know how many there were, but there are probably more than 10,” said Robert Alai Onyango, a blogger in Nairobi. “We believe the attackers were wearing something close to military fatigues.”
Onyango said the attackers appeared to be shooting indiscriminately and “basically from all angles.”
“They surrounded the mosque. … We don’t know why they were surrounding the mosque,” Onyango said.
About 300 students who escaped sought refuge at a Kenya Defense Forces camp, local newspaper journalist Steven Astariko said.
“We are saddened & angered by today’s terrorist attack @ #Garissa Univ.,” the U.S. Embassy in Nairobi tweeted. “Our deepest condolences 2 family/friends of victims.”
The university was established in 2011 and is the only public university in the region.
There are usually 800 students in the dormitories when school is in session, Jackstone Kweyu, dean of students, told Citizen TV. There are 1,000 staff members on a normal workday, he said. And there are usually four guards at the campus gates overnight.
The Kenyan Red Cross and the country’s health ministry are organizing a blood drive to help the victims.
Al-Shabaab’s carnage in Kenya
The dangerously porous border between Somalia and Kenya has made it easy for Al-Shabaab militants to cross over and carry out attacks.
The deadliest assault by Al-Shabaab in Kenya was in September 2013 when the group attacked the Westgate shopping center in Nairobi, killing 67 people.
In a December attack on a quarry, Al-Shabaab militants separated Muslims and executed the non-Muslims, a spokesman for the group said.
Last month, the U.S. Embassy warned of possible attacks “throughout Kenya in the near-term” following the reported death of a key al-Shabaab leader, Adan Garaar.
“Although there is no information about a specific location in Kenya for an attack, U.S. citizens are reminded that the potential for terrorism exists,” the warning said.