"They are inside the compound and there are foreign professors along with hundreds of students," an Afghan interior ministry official said. 

Some students jumped from second floor windows to escape the gunfire and explosions, witnesses and officials said.

The senior interior ministry official said elite Afghan forces had surrounded the university compound.

Early reports were that several gunmen, some wearing suicide vests, were involved, he said.

Foreign staff and dozens of pupils were trapped in the compound hours after the attack began at about 6:30pm local time (3:30am Irish time).

Police said there were a number of dead and injured. A hospital spokesman said at least one student had died and 14 were wounded.

Students and staff tweeted from inside the campus, and after escaping.

#AUAF under attack. I along with my friends escaped and several other of of my friends and professors trapped inside.

— Ahmad Mukhtar (@AhMukhtar) August 24, 2016

Ahmad Shaheer, a student at the university, told Reuters by telephone that he was trapped inside the university.

"We are stuck inside our classroom and there are bursts of gunfire," he said.

"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 escaped.

He injured his ankle making the leap.

"We were in the class when we heard a loud explosion followed by gunfire. It was very close. Some students were crying, others were screaming."

The university's president confirmed a militant attack was underway on the campus.

The attack comes two weeks after two university staff were kidnapped from their car by unknown gunmen.

Their whereabouts are still unknown.

Islamist militant groups, mainly the Afghan Taliban and a local offshoot of Islamic State, have claimed a string of atrocities.

They are aimed at destabilising the country and toppling the Western-backed government of President Ashraf Ghani.