The mangled remains of a vehicle lie near the location of a suicide attack in Kabul, Afghanistan, last Tuesday. ((Ahmad Massoud/Associated Press) )

Afghan authorities are announcing the arrest of seven people in last week's car suicide bombing that killed six NATO soldiers, including three American colonels and a Canadian colonel.

Col. Geoff Parker, 42, who had been the commanding officer of the 2nd Battalion of the Royal Canadian Regiment, a mechanized unit based at CFB Gagetown, N.B., is the highest-ranking Canadian Forces member to die in Afghanistan.

A total of 18 people were killed in the bombing last Tuesday near the destroyed royal palace.

Intelligence service spokesman Saeed Ansari told reporters Monday that the seven were arrested separately over the last week and were under the command of the Taliban's "shadow governor" of Kabul, Daoud Surkha.

It was the deadliest attack against NATO in Kabul in eight months.