Twelve people, including seven students, three police and two security guards, were killed in an attack by gunmen on the American University in the Afghan capital, Kabul, police said on Thursday. Fraidoon Obaidi, chief of the Kabul police Criminal Investigation Department, told Reuters 44 people were wounded, including 35 students. Afghan security forces killed two gunmen who attacked the University, ending an assault on the compound that sent hundreds of students fleeing in panic. The attack at around 6:30 p.m. local time (10 a.m. ET) on Wednesday began with a large explosion that officials said was a car bomb followed by gunfire, as suspected militants battled into the complex where foreign staff and pupils were working. Elite Afghan forces surrounded the walled compound and eventually worked their way inside, according to a senior interior ministry official.

Sporadic gunfire could be heard through the night and, before dawn, police said the operation had concluded.

"The fight is over and at least two attackers are killed," a police official at the scene told Reuters. "Right now a clearance operation is ongoing by a criminal technique team. More details will be announced soon."

Information on casualties remained uncertain, but the Afghan Public health Ministry said one guard was killed and at least 21 people were wounded, six critically. No foreigners were reported among the wounded.

Kabul police chief Abdul Rahman Rahimi told Reuters earlier on Thursday that security forces had rescued around 500 students from the university, which is popular with Afghanistan's elite.

Terrified students recounted barricading themselves in classrooms or jumping from the second floor in order to escape. Most appeared to have got away.

"Many students jumped from the second floor, some broke their legs and some hurt their head trying to escape," Abdullah Fahimi, a student who escaped, told Reuters. 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," he said.

Ahmad Mukhtar, who also fled, said the gunmen had got into the university buildings despite 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," he said. "I ran toward the emergency exit with other students, climbed the wall and jumped outside."

Islamist militant groups, mainly the Afghan Taliban and a local offshoot of Islamic State, have claimed a string of recent bomb attacks aimed at destabilizing the country and toppling the Western-backed government of President Ashraf Ghani.

No one has taken responsibility for the university raid.