A group of militants stormed a university in volatile northwestern Pakistan on Wednesday using the cover of thick fog, police said, with firing inside the campus still going on and two explosions heard.

At least twenty people, one of which was identified as a chemistry professor, has been killed in the attack. Other dead were supposed to be university students.

The militants entered the Bacha Khan University in Charsadda, northwestern Khyber Pakhtunkhwa province, early on Wednesday before opening fire on students and teachers in classrooms and hostels, two police officials said.

Vice Chancellor Fazal Rahim told reporters that several students were stuck inside the campus buildings.

The army and police had moved into the university and a gunfight with the attackers was under way, Deputy Inspector General Saeed Wazir told Reuters. He said it was unclear how many gunmen were involved.(Reuters)