At least 20 people are feared dead and 50 injured in the terror attack on a Pakistani varsity on Wednesday even as a heavy gunbattle continues inside the campus, media reports said.

Heavily-armed terrorists on Wednesday stormed the Bacha Khan University in Charsadda district of Pakistan’s restive northwest Khyber- Pakhtunkhwa province and opened indiscriminate fire on students and teachers. Earlier reports said that a professor was killed in the attack and 10 others were injured.

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.

"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.

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.