A Taliban militant killed at least 95 people and injured more than 150 after driving an ambulance packed with explosives into a crowd in Afghanistan's capital Kabul on Saturday (27 January).
The attack comes just as week after militants stormed an international hotel in Kabul and killed 22 guests.
The blast occurred at about 12.45pm local time (8.15am GMT) in a street that is only accessible to government workers.
The bomb was detonated near the former interior ministry and the European Union offices and High Peace Council.
The attacker reportedly drove past a security checkpoint on his way to the street. Police identified the man at a second checkpoint but were unable to stop him before he detonated the explosives.
Taliban spokesman Zabiullah Mojahid claimed responsibility for the attack.
The Interior Ministry confirmed that at least 95 people died and 158 were injured in the attack.
"The majority of the dead in the attack are civilians, but of course we have military casualties as well," said Nasrat Rahimi, deputy spokesperson for the Interior Ministry.
Rahimi said that four suspects have been arrested and are being questioned.
UN Secretary-General Antonio Guterres condemned the fatal attack. "Indiscriminate attacks against civilians ... can never be justified," a statement from his office read.
The US ambassador to Afghanistan, John R. Bass, described the explosion as "senseless and cowardly".
It is the deadliest terror attack in Kabul in recent months.
This week, Isis terrorists stormed the Jalalabad offices of the charity Save the Children and killed four people in a siege that lasted almost 10 hours.
Last Saturday (20 January), six Taliban gunmen killed 22 people, including 14 foreigners at the Intercontinental Hotel. After a 12-hour standoff, Afghan security forces ended the siege and rescued more than 150 people who had been taken hostage during the gun battle.
In October, 176 people were killed in one week in Taliban bomb attacks. Afghan security forces have struggled to fight the Taliban, who want to re-impose strict Islamic laws in the country, since the US and NATO officially ended their mission in 2014.