The attack in the provincial capital Lashkar Gah occurred near the compound of the governor and three of the British soldiers protecting the area were among those injured, CNN reported, quoting Afghan authorities and the British military.
The target of the attack appeared to be an armored vehicle driven by foreigners, CNN quoted a governor's spokesman as saying.
No other details of the attack were available.
A local official said at least 15 employees of the provincial education department were also among those injured. Khaama Press reported.
There was no immediate claim of responsibility for the attack.