At least one person has been killed after armed men attacked the campus of the American University of Afghanistan in Kabul, according to an official and a student.
At least 26 others were injured in the attack on Wednesday evening, according to health officials.
"Several gunmen attacked the American University in Kabul and there are reports of gunfire and explosions," Mohammad Saleem Rasouly, the head of Kabul's hospitals, told the Reuters news agency.
"[The attackers] are inside the compound and there are foreign professors along with hundreds of students."
Dozens of soldiers cordoned off the area after the attack started on Wednesday evening, when the elite private university is usually packed with students, many of them working professionals doing part-time courses at the facility.
| Many trapped students were tweeting desperate messages for help [Rahmat Gul/AP]
Ahmad Shaheer, a student at the university, told the Reuters news agency that he was trapped inside the university.
"We are stuck inside our classroom and there are bursts of gunfire," he said.
Reporting from outside the locked-down campus in Kabul, Al Jazeera's Jennifer Glasse said that students had begun to "trickle out" as security forces clear the area in pursuit of the gunmen, but some students were "still trapped" inside the university.
"Hospital sources here say at least 16 people are injured, three of them critically... Afghan security forces are in there trying to find the [rest of the] students and get them out safely," said Glasse.
No group has so far claimed responsibility for the attack, which comes as the Taliban step up their summer fighting season against the Western-backed Kabul government.
The attack came after two professors at the university - an American and Australian - were kidnapped in the heart of the capital earlier this month, the latest in a series of abductions of foreigners in the conflict-torn country.
The management of the elite American University of Afghanistan, which opened in 2006 and caters to more than 1,700 students, was not immediately reachable for comment.
|No group has so far claimed responsibility for the attack [File: Melanie Stetson Freeman/The Christian Science Monitor via Getty Images]
Source: Al Jazeera News and agencies