At least 65 people were killed and 325 wounded when a truck loaded with explosives went off in downtown Kabul near the German Embassy on Wednesday morning, Afghanistan Ministry of Health said.
Official sources at the Ministry of External Affairs in New Delhi said that all staff at the Indian embassy were safe.
Some news sites were reporting 50 killed, but this could not be confirmed.
Tolo News Agency said a "truck bomb was detonated close to the German Embassy in Wazir Akbar Khan area, killing and wounding dozens".
Earlier, Tolo had quoted the interior ministry as saying that a "water tanker had been laden with explosives that were detonated on Wednesday".
According to Nato, a massive explosion occurred near the German Embassy at 8.22 am near the Nato Resolute Support headquarter in Kabul.
Foreign troops have arrived at the scene.
Images circulating on social media showed a large plume of black smoke over the city.
The blast occurred during rush hour traffic. It ripped through the diplomatic zone.
There was substantial damage to buildings in the explosion near Zanbaq Square in downtown Kabul.
It said the victims are mostly civilians and a large number of them are from the Roshan mobile company.
All staff in the Indian Embassy are safe but some windows in the building were damaged.
"By God's grace, Indian Embassy staff are safe in the massive #Kabul blast," External Affairs Minister Sushma Swaraj tweeted.
#WATCH Visuals from the blast site in Kabul, Indian embassy staff safe. AP reports 50 people have been killed or wounded #Afghanistan pic.twitter.com/a6rC71DKea
— ANI (@ANI_news) May 31, 2017