Afghan officials say a roadside bombing in an eastern provincial capital killed a police officer and a civilian on June 22.
Abass Sadat, the deputy police chief of Nangarhar Province, said the explosion in the city of Jalalabad also wounded two civilians.
Sadat said the bomb was probably detonated by remote control after being planted near a police checkpoint.
There was no immediate claim of responsibility for the attack.
The top United Nations official in the country, Nicholas Haysom, warned on June 22 that Afghanistan could face "retaliatory acts of vengeance and an escalating spiral of violence."
He said his concerns were fueled by a series of attacks against civilians in recent months and deadly violence that has continued during the Muslim holy month of Ramadan.