6 Americans among 15 killed in suicide bombing of NATO convoy in Afghanistan (UPDATES)

A suicide bomb attack killed six Americans and at least nine Afghan civilians in Kabul on Thursday.

The attack is the deadliest in Kabul this year, according to the Guardian. The last suicide bombing in the city occurred two months ago and killed nine Afghan civilians.

More from GlobalPost: Afghan suicide bombers strike during US official Chuck Hagel's visit

Today's bomber struck a NATO convoy. John Manley, a spokesman for the NATO-led international coalition, said that the foreigners killed included two troops and four civilian contractors.

The total death toll stood at 15, with two children among the dead, according to the Associated Press.

The AP later reported that two US troops were among the six foreigners who died, adding that the attacker rammed a car packed with explosives into the convoy as it passed the home of an Afghan lawmaker.

US military contractor DynCorp International said the four civilian contractors who died worked for them and were in Afghanistan to help train Afghan security forces, the Los Angeles Times reported.

The early-morning explosion happened in the Shah Shahid neighborhood.

Some of the bodies of those killed were so badly charred that neither their gender, nor their nationality was immediately clear, reports said.

Footage of the scene reportedly showed the road scattered with debris and mangled vehicles as emergency workers tended to the injured.

While most attacks in Kabul are linked to the Taliban, Thursday's attack was claimed by the smaller Hezb-e-Islami Gulbuddin militant group, led by a local warlord, Gulbuddin Hekmatyar, the Wall Street Journal wrote.

The Journal quoted him as saying:

"We have been following these vehicles for over a week. We don't have any problems with the Afghans, and we are not targeting them. We are targeting the foreigners."

The group had previously claimed an attack in Kabul on a minivan carrying crew from an aviation company contracted by the US Embassy, which killed at least 12 people.

The Post cited a Kabul police spokesman as saying Thursday's blast was so powerful "it set the nearby office buildings ablaze."