At least 13 people were killed and 36 others were wounded when gunmen attacked the American University of Afghanistan in Kabul, Afghan officials said early Thursday. 

Approximately 12 hours after the attack began Wednesday evening, Kabul police chief Abdul Rahman Rahimi said that about 700 students had been rescued from the university compound. The State Department announced Thursday no Americans were killed or wounded.

Details on the victims were not immediately available, but Hedayatullah Stanikzai, an official with the Ministry of Public Health, said a guard employed by the university was among the dead. Reuters reported that both gunmen involved in the assault were also killed. 

There were no immediate claims of responsibility for the attack on the university, which was established in 2006 to offer liberal arts courses modeled on the U.S. system, and has more than 1,000 students currently enrolled.

Witnesses said the gunmen got into the university despite tight security measures, including armed guards and watchtowers. 

I finished my class and was about to leave when I heard a few gunshots and a huge explosion, followed by more gunfire," student Ahmad Mukhtar told Reuters. "I ran toward the emergency exit with other students, climbed the wall and jumped outside."

Another student described jumping out of a second-floor window in an attempt to escape the attack.

"Many students jumped from the second floor, some broke their legs and some hurt their head trying to escape," said Abdullah Fahimi, a student who injured his ankle making the leap.

Dozens of students and foreign staffers who could not get away barricaded themselves inside classrooms and safe rooms.

Associated Press photographer Massoud Hossaini was in a classroom with 15 students when he heard an explosion on the southern flank of the campus.

"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 inside the classroom, pushing chairs and desks against the door, and staying on the floor. Hossaini said at least two grenades were thrown into the classroom, wounding several of his classmates.

Hossaini and about nine students later managed to escape from the campus through an 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.

Hossaini and the other students took refuge in a residential house near the campus, and were later safely evacuated by Afghan security forces.

Dejan Panic, the program director at Kabul's Emergency Hospital, said 18 people wounded in the attack, including five women, had been admitted. He said three were "seriously" wounded, probably from automatic gunfire.

A car bomb had exploded outside a school for the blind next door before at least one attacker fired at the university campus from that school building, a police officer at the scene told The New York Times.

The U.S. Embassy was working to account for all of its personnel, State Department spokeswoman Elizabeth Trudeau told reporters. She said the State Department condemned the attack. 

The U.S. military was assisting Afghan forces who responded to the attack, U.S. Army Colonel Michael T. Lawhorn told Fox News. "These advisors are not taking a combat role, but advising their Afghan counterparts."

The attack was the second time in less than three weeks that the American University has been targeted by militants.

Two of its professors were kidnapped at gunpoint in Kabul on August 7. The professors were identified as Kevin King, an American, and Timothy Weeks from Australia. Men in military uniforms reportedly abducted them as they traveled between the campus and their home in Kabul. The professors' whereabouts are unclear.

Fox News' Rich Edson, Conor Powell, Lucas Tomlinson and The Associated Press contributed to this report.

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