The Taliban faction behind a massacre at a university in northwest Pakistan this week issued a video message Friday, January 21 vowing to target schools throughout the country, calling them "nurseries" for people who challenge Allah's law, Daily Mail reports.

The video, which spread rapidly on Facebook but was not released on official media accounts for the Tehreek-e-Taliban Pakistani (TTP), shows Khalifa Umar Mansoor, whose faction claimed responsibility for the attack on Bacha Khan university Wednesday.

Heavily armed gunmen stormed the campus in Charsadda in northwest Pakistan, killing 21 people in an attack that had chilling echoes of a 2014 assault on a school in nearby Peshawar, also claimed by Mansoor's faction.

The rampage threatened to shatter the sense of security growing in the troubled region a year after the Peshawar attack, which left more than 150 people dead - mostly children.

In the video issued Friday, Mansoor said his faction had attacked the university "because this is the place where lawyers are made, this is the place that produces military officers, this is the place that produces members of the parliament, all of whom challenge Allah's sovereignty."

Instead of targeting armed soldiers, he said, "we will target the nurseries that produce these people."

"We will continue to attack schools, colleges and universities across Pakistan as these are the foundations that produce apostates. We will target and demolish the foundations," he said.