The NATO Resolute Support mission, whose offices were near the blast, said the two service members were "killed in action," without providing details or releasing their names. The American service member was the fourth killed in the past two weeks in Afghanistan.
"Peace with a group that is still killing innocent people is meaningless," President Ashraf Ghani, whose government has been shut out of the U.S.-Taliban talks, said in a statement.
Another 42 people were wounded, Interior Ministry spokesman Nasrat Rahimi said. Surveillance footage showed the bomber's vehicle turning into a checkpoint and exploding — and a passer-by trying to sprint away just seconds before the blast.
The Taliban said they targeted vehicles of "foreigners" trying to enter the heavily guarded Shashdarak area where Afghan national security authorities have offices. British soldiers at the scene retrieved what appeared to be the remains of a NATO vehicle.
Once again, stunned civilians made up most of the victims. The Taliban has said its attacks are meant to strengthen its position in talks with the U.S. and that civilians should stay away from potential targets linked to the Afghan government or foreign "invaders."
"I don't know who brought us to the hospital and how," said one of the wounded, Nezamuddin Khan, who was knocked unconscious and woke up in a local hospital.
The explosion followed a Taliban attack against a foreign compound late Monday that killed at least 16 people and wounded more than 100, almost all of them local civilians. An Associated Press reporter on the phone with the U.S. Embassy when Thursday's blast occurred heard sirens start blaring there.
The violence continued hours later when the Taliban claimed responsibility for a car bombing outside an Afghan military base in the Logar provincial capital, Puli Alam, with local officials saying four civilians were killed and 11 others wounded.
Then the Afghanistan Independent Human Rights Commission confirmed that its acting leader in Ghor province, Abdul Samad Amiri, had been kidnapped by the Taliban while traveling and shot dead late Wednesday.
The especially violent week occurs as U.S. envoy Zalmay Khalilzad is in Kabul briefing Ghani and other Afghan leaders on the U.S.-Taliban deal to end nearly 18 years of fighting that he says just needs President Donald Trump's approval to become a reality. Khalilzad has not commented publicly on this week's attacks.
The Afghan government has raised serious concerns about the deal, including in new comments Thursday as the latest Kabul bombing occurred. The agreement was moving with "excessive speed," presidential adviser Waheed Omer told reporters, warning of difficult days ahead.
"Afghans have been bitten by this snake before," Omer said, recalling past agreements from which the Afghan government has been sidelined. "Where there is no feeling of ownership there is no safety," he said.
The Taliban, at their strongest since their 2001 defeat by a U.S.-led invasion, have refused to negotiate with the government, calling it a U.S. puppet. And yet the U.S. hopes its deal with the Taliban will bring the militant group to the table for intra-Afghan talks to begin ahead of Afghanistan's presidential election on Sept. 28.
The Afghan government has said it shares the concerns raised this week by several former U.S. ambassadors to Afghanistan. They warned that a full U.S. troop withdrawal that moves too quickly and without requiring the Taliban to meet certain conditions, such as reducing violence, could lead to "total civil war" such as the one that engulfed the country in the 1990s after a rapid Soviet pullout and before the Taliban swept into power.
Khalilzad has said the first 5,000 U.S. troops would withdraw from five bases in Afghanistan within 135 days of a final deal. Between 14,000 and 13,000 troops are currently in the country. However, the Taliban want all of the approximately 20,000 U.S. and NATO troops out of Afghanistan immediately.
The U.S. seeks Taliban guarantees that they will not allow Afghanistan to become a haven from which extremist groups such as al-Qaida and the local affiliate of the Islamic State group can launch global attacks.
The Afghan president, who has been shown the U.S.-Taliban deal but not allowed to keep a copy, has insisted that this month's election be held on time. He seeks a second term and a strong mandate to negotiate with the militant group on the country's political future. He rejects talk of an interim government, an idea that has gained such traction among Afghans that many other presidential candidates have barely campaigned.
Ghani's adviser, Omer, acknowledged Thursday the risks of holding another chaotic election after Afghanistan's presidential one in 2014 and last year's parliamentary vote. This election must happen on time, he said, but said a vote that is not transparent will "cause challenges."