At least 19 persons were killed when armed gunmen stormed Bacha Khan University on Wednesday morning in Pakistan's northwest Khyber-Pakhtunkhwa province and opened indiscriminate fire.

The terrorists reportedly entered the campus at around 9 am and nine explosions were heard since then.

Around 3,000 people are reportedly trapped inside the university campus and at least 60 students are injured.

According to TV reports Pakistani Taliban have claimed resposnsibilty for the attacks.

Heavy firing is underway inside the campus in the province's Charsadda town, some 50 kilometres from here, local media reports said. The army has been called in to neutralize the terrorists.

"Armed men stormed into the university premises early this morning," Sardheri police officials said, adding that two explosions were heard inside the building.

Eyewitnesses also said they heard explosions. They said three armed men had entered the premises of the varsity.

Officials added that two guards were injured at the gate besides one other person.

Meanwhile, extensive firing continues in the area and heavy contingents of elite force have been deployed.

Taliban militants massacred over 150 people, mostly students, in an attack on an army-run school in Peshawar in December, 2014.