Heavily-armed terrorists today stormed a university in Pakistan's restive northwest Khyber-Pakhtunkhwa province and opened indiscriminate fire on students and teachers, killing at least one professor and two students and injuring at least 10 persons, reports PTI.

However, Pakistan's Dawn reported that death toll claims run from 15 to 60 killed. DIG Saeed Wazir said two attackers had been killed.

Security personnel are still entering the school to control the situation. Wazir told Reuters he believes most of the students had been rescued but several gunmen remained at large inside the university.

The remaining terrorists are giving stiff resistance to security forces as they continue the clearance operation. Intelligence sources say eight to 10 terrorists are still inside the school.

The terrorists scaled the university walls and opened fire. Multiple blasts were heard along with continuous heavy gunfire.

At least three gunmen entered the Bacha Khan University in Charsadda district of Khyber-Pakhtunkhwa, some 50 kms, south west of Peshawar, and opened fire on students and teachers in classrooms and hostels, media reports said.

@AsimBajwaISPR tweeted saying, that Army troops have reached the university and the area has been cordoned off. Clearance ops have begun and an air surveillance is being done.

"Armed men stormed into the university premises early this morning," police said, adding that two explosions were heard inside the building and firing was still going on.

The families of students have lined up outside the school. Journalists and all other non-essential personnel have been asked to stay back in order to not interfere with the ongoing security operation. Up to 20 ambulances have entered the university to rescue the injured, the Dawn reported.

Geo TV reported that Professor Hamid of chemistry department was killed while 10 other persons were injured. "A teacher of the varsity after evacuation said Chairman Chemistry Department Hamid has been martyred by the firing of the militants," it said, adding the terrorists barged into Hamid's room and fired at his head, killing him instantly.

At least 10 persons, including security guards, sustained multiple injuries in the terrorist attack, police said. The injured were shifted to hospital.

An emergency has been imposed in all hospitals in the town. University Chancellor Dr Fazal Rahim said there are over 3,000 students present inside the university along with an additional 600 guests who are present for a poetic symposium to mark the death anniversary of Khudai Khidmatgar Khan Abdul Ghaffar Khan alias Baacha Khan who died on January 20, 1988.

The terrorists barged into the university where the event was being attended by a large number of students. Khyber Pakhtunkhwa's Member of Provincial Assembly Arshad Ali said the attackers entered the university after scaling its walls, Dawn reported.

It quoted a woman inside the university as saying that intense firing is underway. Citing DSP Charsadda, the state-run PTV said that three armed men entered the university premises and opened fire.

A large contingent of security forces had reached the site and started evacuating students. Army troops, police and personnel of Elite Force engaged the militants into gunfight. Security forces are not sure how many terrorists are holed up inside the university. The Taliban militants massacred over 150 people, mostly students, in an attack on an army-run school in Peshawar in December, 2014.