The Taliban has claimed responsibility for a suicide attack that killed at least 17 people after a car rammed into a convoy of foreign troops in Kabul, the Afghan capital.
The attack on Saturday killed 13 personnel from the NATO-led International Security Assistance Force (ISAF), according to an ISAF spokesperson, as well as a police officer and three Afghan civilians.
"Initial reports indicate that 13 International Security Assistance Force service members died following an improvised explosive device attack in Kabul earlier today," the force said in a statement.
One of those killed was a Canadian solder, while the rest are understood to be US troops and US contractors.
The attacker detonated explosives in a Toyota vehicle at 11:20am local time in the southwest of the city just as a military bus carrying US soldiers was passing by, becoming the deadliest attack against foreign troops in Kabul for many years.
The Taliban claimed responsibility for the attack in a text message to media outlets sent by Taliban spokesperson Zabiullah Mujahid.
Al Jazeera's Bernard Smith, reporting from Kabul, said the incident is indicative of an attack where a suicide bomber will "drive up and down the roads waiting for a target".
Kabul police identified the dead civilians as two young students and an adult male cyclist.
NATO helicopters were seen airlifting the wounded from the attack site in the west of the city.
"It was a very strong bomb,'' said Gulam Saki, a witness at the scene who spoke to the AP news agency.
"Three civilians were killed, a man, a woman and one child, and two bodies are still under the vehicles," he said.
George Little, the Pentagon press secretary, told reporters that the attack is a reminder for the US of its mission in Afghanistan.
"Continuing our aggressive pursuit of the enemy will honour their sacrifice, and he [the US Secretary of Defense] is determined that the United States -- working closely with our Afghan and NATO partners -- will do precisely that."
Just before the Kabul blast, an Afghan soldier opened fire on foreign forces, killing three Australian army trainers in the south of the country, NATO and a local commander said.
The alliance force said two service members were killed and one other later died of his injuries after "an individual wearing an Afghan National Army uniform apparently turned his weapon on Afghan and coalition forces."
It said the attacker was also killed in the incident but gave no further details.
In the eastern province of Kunar, a suicide bomber, said to be in her twenties, blew herself up outside a branch of the National Directorate of Security (NDS) on Saturday, a local news service report said.
After waiting at a female-only bus stop for several hours, the attacker fired at the gate of the NDS offices in the provincial capital of Asadabad with a pistol before detonating her explosives, police said.
Sources told Al Jazeera that one intelligence official was shot after the attacker was ordered to stop just short of the NDS gate.
The attack left another five people, two civilians and three security officials, injured, according to hospital statements to local Afghan media.