A twin suicide attack on a convoy of buses carrying Afghan police cadets has left 37 people dead.
The attack took place in Paghman district, about 12 miles west of the capital Kabul, and left another 40 people injured.
Local governor Mousa Rahmati said the first suicide attacker struck two buses carrying trainee policemen, and a second bomber targeted those who rushed to the scene to help and hit a third bus.
Four civilians were among those killed.
The cadets were returning from a training centre in Wardak province and were heading to the capital on leave.
The Taliban claimed responsibility for the attack. Spokesman Zabihullah Mujahid said the attack was the work of two suicide bombers who detonated their explosives 20 minutes apart.
The office of Afghan president Mohammed Ashraf Ghani described the bombing as an "attack on humanity", and ordered an interior ministry investigation into the incident.
In a statement, the US Embassy in Kabul condemned the attack. "This cruel and complete disregard for human life during the holy month of Ramadan is abhorrent," the statement said.
Earlier At least 30 people have been killed in a suicide bombing which attacked a bus carrying trainee policemen in Afghanistan.
Mousa Rahmati, the district governor of Paghman, said the attack took place about 12 miles west of the capital Kabul.
He said the trainee police officers were returning from a training centre in Wardak province and were heading to the capital on leave.
The Taliban has claimed responsibility for the attack.
A spokesman for the Afghan interior ministry confirmed the location of the attack and said a loud explosion had been reported, but he did not have any further details on the incident.
Taliban spokesman Zabihullah Mujahid said the attack was the work of two suicide bombers.
He said the first, on foot, targeted the bus carrying the trainee policemen and their instructors. Then a suicide car bomber attacked 20 minutes later, when policemen had arrived at the scene to help.