An explosion followed by gunfire rocked capital Kabul on Wednesday, police said.
Basir Mujahed, spokesman for the Afghan National Police in the capital, said a car bomb exploded in Sarak-e-Nau on the main Kabul-Jalalabad highway.
The area has a number of security installations including a compound of foreign troops and aid agencies.
Local Ashna Radio reported that a private security firm, G4S, working for the British troops has been targeted.
At least eight critically wounded people have reportedly been rushed to the hospital.
There has been no immediate claim of responsibility.