On Monday, three gunmen stormed the campus of Kabul University in Kabul, Afghanistan, killing 35 people and wounding many others.

The attack began around the time government officials were expected to arrive at the campus for the opening of an Iranian book fair.

The three gunmen were later killed during a fight with security forces, according to the local sources.

Although the Taliban has denied its involvement in the attack, First Vice President Amrullah Saleh alongside some Afghan government officials attributed it to the group.

The Afghan government declared Tuesday as a national day of mourning.