Explosion heard in central Kabul, smoke seen near U.S. embassy - witnesses

A forensic expert inspects through a window of a government security building after a blast in Kabul, Afghanistan April 19, 2016. REUTERS/Ahmad Masood

KABUL (Reuters) - A Taliban suicide bomb and gun assault on a government security building during Tuesday morning rush hour in central Kabul killed at least 28 people and wounded more than 320, in the deadliest single attack in the Afghan capital since 2011.

President Ashraf Ghani condemned the assault "in the strongest possible terms" in a statement from the presidential palace, located only a few hundred metres away from the scene of the blast.