Afghanistan on Sunday declared a day of national mourning as the toll of those killed by a huge bomb hidden in an ambulance in Kabul went past 100 dead, as insurgents struck in the city for the second time in a week.
At least 103 people were killed and 235 wounded in Saturday's lunchtime attack claimed by the Taliban, which caused panic in the war-torn capital and overwhelmed its hospitals.
Kabul was in despair on Sunday after the worst attack in the Afghan capital in months.
A week ago, the Taliban killed more than 20 people in a siege of the city's Intercontinental Hotel. Another six people were killed in an assault claimed by Islamic State on the office of aid group Save the Children in the eastern city of Jalalabad.
Despite pressure on President Ashraf Ghani's Western-backed government to improve security, the attacks show no sign of abating, giving rise to helpless anger among residents.
Interior minister Wais Barmak said at least two vehicles painted as ambulances were involved in the attack, one of which blew up at when it was stopped at a police checkpoint.
Kabul remained on high alert as the presidential palace declared a national day of mourning for Sunday, with flags flying at half-mast.
Central Kabul was unusually quiet on Saturday, a normal workday in Afghanistan, with little traffic and few people on the street. Security checkpoints have been beefed up, particularly in the streets near the blast scene, as the city braced for the possibility of further violence.
A security alert issued on Sunday warned that the Islamic State group, which claimed a deadly attack on Save the Children's office in Afghanistan's east on Wednesday, was planning to attack supermarkets and shops in Kabul frequented by foreigners.
US President Donald Trump called for "decisive action" against the Taliban over the assault as other international leaders also condemned the attack.
Afghan authorities gave an updated toll today for those killed and maimed in the huge blast.
"Unfortunately a number of wounded people have died in hospital. The number of martyrs is now 103 and wounded is 235," interior minister Barmak told reporters.
Health ministry spokesman Waheed Majroh told reporters earlier on Sunday that most of the injured were men.
Ordinary Afghans took to social media to express their anguish and sorrow at rapidly worsening security as the Taliban and IS militants step up attacks on Kabul, turning it into one of the deadliest places in Afghanistan for civilians.
The blast happened in a crowded area of the city where several high-profile organisations including the European Union have offices.
The force of the explosion shook the windows of buildings hundreds of metres away and caused some low-rise structures in the immediate vicinity to collapse.
The scene of the attack was scattered with body parts, blood and debris. Children were among the wounded.
The government has blamed the Taliban-affiliated Haqqani Network, which Afghan and Western officials suspect of involvement in at least some of the recent attacks in the capital.
The suicide bomber passed through at least one checkpoint in the ambulance, saying he was taking a patient to Jamhuriat hospital, an interior ministry spokesman said on Saturday.
"At the second checkpoint he was recognised and blew (up) his explosive-laden car," Nasrat Rahimi said.
Rahimi told a news conference later that most of the victims were civilians. Four suspects had been arrested.
The attack came exactly a week after Taliban insurgents stormed Kabul 's landmark Intercontinental hotel and killed at least 25 people, the majority foreigners.
But there is still confusion over the true toll from that attack with conflicting figures given by officials and Afghan media reporting higher numbers.
Some foreign organisations are reassessing their presence in Afghanistan following the spate of deadly violence.
The Aga Khan Foundation is moving its foreign staff out of the country, several sources told AFP. At least one Western humanitarian group is relocating its foreign staff to other cities in Afghanistan, a source said.