Officials in eastern Afghanistan say a suicide car bomber targeted a convoy of U.S. forces Friday, killing at least four people and wounding 12 others.
The attack took place near the airport in Jalalabad, capital of eastern Nangarhar province.
The Taliban has claimed responsibility for the bombing.
A provincial police spokesman said the bombing victims were all Afghan civilians and no U.S. soldiers were hurt.
Jalalabad is where an Afghan solder two days ago killed an American counterpart and wounded eight others. There were no claims of responsibility for Wednesday's so called "insider attack."
Escalation of violence
Elsewhere in Afghanistan Friday, a roadside bomb killed at least 12 civilian passengers in Ghazni province.
All the victims, including women and children, were members of the same family, said a provincial spokesman. There was no immediate claim of responsibility.
And in Kabul, a suicde car bomber struck a NATO convoy and according to initial reports at least one civilian was wounded. The Taliban claimed responsibility for the attack.
On Thursday a group of Taliban suicide bombers stormed a judicial complex Thursday in the northern Afghan city of Mazar-i-Sharif, killing at least 10 people and wounding dozens of others. Afghan security forces killed some attackers, while other assailants blew themselves up during the siege that lasted for over six hours.
The Taliban claimed responsibility for the raid, saying it was meant to avenge “mistreatment of prisoners” in jails across the country and failure of the judicial system to prevent them.
The escalation of militant violence comes as the traditional "spring fighting" season is about to begin.
The United Nations expressed concern over the violence.
"These incidents highlight once again the tragic reality that it is Afghan civilians who bear the brunt of the reckless use of violence," said the U.N. Secretary General's Special Representative for Afghanistan and head of UNAMA, Nicholas Haysom.