Kenyan officials say 147 people are dead after al-Shabab militants attacked a university in northeastern Kenya Thursday.
About 160 students are still unaccounted for, Kenya's interior ministry said.
Interior Minister Joseph Nkaissery spoke as special forces tried to clear the assailants off the campus of Garissa University College, about 370 kilometers (230 miles) east of Nairobi.
A reporter for VOA's Somali news service reported hearing gunfire and explosions coming from the campus. Nkaissery said four assailants had been killed and security forces had intensified a rescue operation.
He added that about 500 of the 815 students had been accounted for later Thursday.
Nkaissery also ordered a dusk-to-dawn curfew in Garissa and in the nearby counties of Wajir, Tana River and Mandera - all near the Somali border.
Somali militant group al-Shabab claimed responsibility for the assault, saying it was revenge for Kenyan troops fighting in Somalia.
Early morning attack
Witnesses said the assailants began the attack about 5 a.m. near the classrooms and then worked toward the residence halls. Police said gunmen stormed the campus and opened fire "indiscriminately."
The Kenyan Red Cross said the gunmen were holding an "unknown number of student hostages."
The number of attackers is not clear, although witnesses reported seeing four or five armed men on campus. The Kenyan Interior Ministry said earlier that one suspect was arrested trying to flee the scene, and that security forces had the assailants "cornered" in a residence hall.
In a televised statement to the nation, President Uhuru Kenyatta said police and the Interior Ministry are coordinating the government response to the attack. He urged Kenyans to remain calm and give authorities any information they may have in connection with all security threats.
Kenyatta also offered his condolences to the victims' families: “We continue to pray for the quick recovery of the injured and the safe rescue of those still being held hostage.”
Christian or Muslim
Witnesses said the attackers were asking students whether they are Christian or Muslim. A spokesman for the militant group said its fighters are holding Christian hostages inside the university residence but have released all the Muslims.
Another spokesman told the French news agency AFP that the group's mission is to "kill those who are against the Shabab."
The U.S. ambassador to Kenya, Robert Godec, said the United States "strongly condemns al-Shabab's heinous terrorist attack" and stands "shoulder to shoulder with the government and people of Kenya in the effort to end the scourge of terrorism."
Kenyan authorities named alleged al-Shabab commander Mohamed Kuno as the mastermind of the attack. A security brief seen by VOA said Kuno was a former madrassa teacher in Garissa in the late 1990s and is now said to be al-Shabab's chief for external operations against Kenya.
Kenya's Red Cross said 65 casualties were taken to a local hospital, most with gunshot wounds. It said five of the wounded were airlifted to Nairobi for treatment.
Student details attack
Students in campus housing were awakened Thursday by the sound of gunfire. Student Beatrice Mathai told VOA she and fellow students fled when they heard what she called a heavy exchange.
"We run from where we were, kneeled down and looked out towards the football club," Mathai said. "Finally, we jumped over the building’s wall. Before the attack we were 29 students, now we are seven, we are very frightened and even do not know where we are now. "
Student Mercy Chebet told VOA she and other students evacuated the dormitories as the gunmen approached.
“It started in the classes and we were in the hostels sleeping, so when we heard the bullets, we just moved out of the hostels and ran to the field,” Chebet said. “When we were in the field, they came to the hostels and they were shooting where we were."
She said the gunmen then moved into the dormitories and began firing. She said she spoke by phone to some friends still inside.
“They're inside, they are being held hostage and the policemen are outside. I don't know what will happen next,” Chebet said.
Collins Wetangula, the vice chairman of the student union, told The Associated Press he was preparing to take a shower when he heard gunshots coming from Tana dorm, which hosts both men and women, 150 meters (yards) away.
He said that when he heard the gunshots he locked himself and three roommates in their room. When the gunmen arrived at his dormitory, 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,” he said. “With each blast of the gun, I thought I was going to die.”
The gunmen then started to shoot rapidly and it was as if there was an exchange of fire, he said.
“The next thing, we saw people in military uniform through the window of the back of our rooms who identified themselves as the Kenyan military,” Wetangula said. The soldiers took him and around 20 others to safety.
The University of Nairobi warned its students last week that al-Shabab was planning attacks on Kenyan institutions, including a "major university."
In an email obtained by VOA with the subject "TERROR THREAT" dated March 26, the University of Nairobi's security office said information about a possible attack was "being processed by the relevant government agencies."
It is not clear yet that Garissa University received or posted the same warning.
The town of Garissa, in northeastern Kenya, is about 200 kilometers (125 miles) from the border with Somalia and has, in recent years, been the site of sporadic gun and grenade attacks blamed on al-Shabab.
Al-Shabab is known for assaults on large buildings, such as the Westgate mall in Nairobi in 2013, and Somalia's presidential palace, which it attacked twice last year. The Westgate attack killed more than 60 civilians.
Last week al-Shabab claimed responsibility for a deadly siege on a Mogadishu hotel that lasted more than 12 hours and in which at least 24 people, including six attackers, were killed.
Kenyatta announced that he would fast-track the training of 10,000 additional police, saying the country has “suffered unnecessarily due to shortage of security personnel.”
Mohamed Farah Shire contributed to this report from Garissa. Some material for this report came from Reuters and AP.