Updated 10:30 p.m. ET with police announcements

Police in Kabul say a violent attack on the American University of Afghanistan has ended with as many as 12 people killed.

The Associated Press reports Kabul police Chief Abdul Rahman Rahimi says the dead included one campus guard. Earlier, hospital officials had said one of the dead was a student. The Reuters news agency quotes its sources as saying police killed two attackers.

Gunmen launched the assault on Wednesday evening, and students and staff hunkered down in place or fled for their lives, witnesses say. For hours overnight, police worked their way through the university, searching for attackers and evacuating students.

The AP quotes Rahimi as saying that about 700 students were rescued, and more than 30 people were injured including one foreign teacher.

There has been no public claim of responsibility.

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As Jennifer Glasse, reporting from Kabul, tells our Newscast unit.

"Right now there are dozens of Afghan police, security forces, special forces. They've surrounded the campus," Glasse says. Here's more:

"The explosion went off at about 7 o'clock here and a number of attackers got into the campus of the American University, where students were in the middle of evening classes. So dozens if not hundreds of students are inside the university and a number of the buildings there. We've heard some gunfire — it's been fairly quiet but a few sporadic bursts of gunfire and shots."

Afghan security forces have been combing the university grounds in search of the perpetrators and any students still hiding, Glasse reports.

The president of the university, Mark English, had told The Associated Press that a militant attack was underway. He said they "are trying to assess the situation."

It's still unclear exactly how many attackers participated and whether they belong to a specific militant group. As Glasse reports, police say at least three gunmen were involved.

Student Freshta Ibrahimi tells NPR that she was eating dinner with friends on campus when explosions and gunfire rang out. They started running toward the emergency door to try to get to the street.

"When we were running ... we were hearing the fire of guns again and everybody was shouting 'Let's run, run! They're in the campus and they're firing!' " Ibrahimi says. "I myself started crying when I heard the gunfire and how it was close to me." She says she eventually made it out to safety. After her group ran to a main street away from the campus, "I couldn't stand on my feet and I couldn't breathe," she said.

Pulitzer Prize-winning photographer Massoud Hossaini tweeted that he was stuck on campus and heard gunshots and explosions, noting "this maybe my last tweets."

But he escaped. He spoke with the AP about the harrowing experience, saying he was in a classroom with 15 students when he heard an explosion:

" 'I went to the window to see what was going on, and I saw a person in normal clothes outside. He shot at me and shattered the glass,' Hossaini said, adding that he fell on the glass and cut his hands."The students then barricaded themselves into the classroom, pushing chairs and desks against the door, and staying on the floor. Hossaini and about nine students managed to escape from the campus through a northern emergency gate." 'As we were running I saw someone lying on the ground face down, they looked like they had been shot in the back,' he said."

The attack comes just a few weeks after two foreign professors were kidnapped at gunpoint near the school. They have not been located.

In 2014, two employees of the American University of Afghanistan were killed in an attack on a Kabul restaurant. The deaths shook a school that had been largely insulated from violence.

"From behind its fortified walls, the university has operated relatively unscathed since it opened in 2006," NPR's Jacki Lyden noted at the time. "It's benefited from a huge infusion of cash from the United States, which sees the campus as an incubator of talent and entrepreneurship."

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