Nine killed as militants raid Kabul's American University

However, no group has so far claimed responsibility for the assault

At least nine people were killed after militants stormed the American University of Afghanistan in Kabul, officials said on Thursday, in a nearly 10-hour raid that prompted anguished pleas for help from trapped students.

Explosions and gunfire rocked the campus after the attack began on Wednesday evening, just weeks after two university professors -- an American and an Australian -- were kidnapped at gunpoint near the school.

No group has so far claimed responsibility for the assault, but it occurred as Taliban insurgents ramp up their nationwide summer offensive against the Western-backed Kabul government.

"Seven students were martyred, and 30 other students and lecturers were wounded," interior ministry spokesman Sediq Sediqqi told AFP, adding that two policemen were also killed.

Hundreds of students were rescued during the overnight operation, he said, many of whom tweeted desperate messages for help, with some using classroom furniture to barricade the doors.

Among them was Associated Press photojournalist Massoud Hossaini, who was said to be wounded and later managed to escape with some fellow students.

The attack began just after dusk, when the private university is usually packed with students, many of them working professionals doing part-time courses.

"I heard explosions and gunfire is going on close by... our classroom is filled with smoke and dust," an anxious student told AFP by telephone, before fleeing the campus.

Authorities refused to confirm whether any hostages had been taken.

NATO military advisers were helping Afghan forces to respond to the attack, a US official said, without specifying how many troops were involved.

Many of the wounded were rushed into waiting ambulances outside the university on stretchers, as erratic gunshots rang out through the night from inside the complex.

"We send our thoughts and prayers to the families of those killed and our heartfelt wishes for a speedy recovery to those wounded," the US National Security Council said in a statement, strongly condemning the attack.

The elite American University of Afghanistan, which opened in 2006 and enrolls more than 1,700 students, is seen as a high-profile target for militants partly because it attracts foreign faculty members.

The two foreign professors at the university were seized from their vehicle on August 7, as the kidnappers smashed the passenger window and hauled them away at gunpoint.

It was apparently the first reported abduction related to a private university in Afghanistan.