Many people have been killed and wounded in a blast that rocked central Kabul during the morning rush hour on Tuesday, President Ashraf Ghani said.
Afghanistan's Tolo News channel said at least 28 people were killed and more than 200 others injured in the coordinated attack.
The attack, claimed by the Taliban, apparently targeted the offices of Afghanistan's main security agency.
In a statement, the Presidential Palace condemned the attack "in the strongest possible terms," saying a number of people had been killed or wounded.
A spokesman for an emergency hospital in the city told Reuters that the facility had received eight lightly wounded Afghan soldiers.
A thick plume of black smoke was seen rising from the vicinity of the sprawling US embassy in the Afghan capital after the powerful blast.
Warning sirens were sounded at the embassy compound, which is also close to NATO headquarters in Afghanistan.
An Afghan official said a possible bomber carried out the attack which was followed by gunfire. Interior Ministry spokesman Sediq Sediqqi said the area has been surrounded by security forces.
Taliban militants have stepped up their attacks against foreign troops and Afghan security forces since announcing the start of their spring offensive last week.