By Atia Abawi and Fazal Ahad, NBC News

KABUL, Afghanistan — Six Americans were killed when a suicide bomber targeted a convoy carrying foreign troops in Kabul on Thursday, according to a NATO source.

The victims included two soldiers and four civilian contractors, the source added.

Officials said at least six Afghan civilians had also died.

Kabul police spokesman Hashmatullah Stanikzai said the attacker detonated a Toyota Corolla. He added that 35 people had been injured.

The powerful blast took place at around 8 a.m. local time (11.30 p.m. ET Wednesday).

“It was a powerful explosion and some of the dead civilians were badly burned and cannot be recognized,” Kane Backlash, a spokesman for Afghanistan’s Health Ministry, told Reuters.

Hizb-i-Islami, an insurgent group which is allied with the Taliban, claimed responsibility for the attack. In September, the group said it had launched an attack near Kabul’s airport that police said killed 12 people.
Reuters contributed to this report.