Stung by criticism that it had misrepresented the details of the Benghazi attack last year, the State Department rushed out a late-night statement confirming that no Americans had been injured.
James Cunningham, the US ambassador to Kabul, condemned "this senseless loss of life".
"We are reminded again of the very real human toll exacted by terrorism. The perpetrators of this attack have shed Afghan blood on Afghan soil," he said.