"We think the bomb was attached to a motorbike that was parked outside the building," police commander Bashir Khan said as he surveyed the site of the blast in Kandahar. "There are many casualties."
A reporter for The Associated Press said he saw three bodies lying on the ground covered in blood and several wounded people being carried away.
The site of the blast is up against a concrete wall that surrounds the heavily guarded police headquarters. Several cars and motorbikes in the area were destroyed, but the wall and the buildings inside the police compound were not damaged.
Afghan and Canadian troops cordoned off the area. The attack is the latest in a string of bombings in Kandahar, a former Taliban stronghold. The violence has raised fears for this country's nascent democracy four years after the Taliban were ousted for hosting Osama bin Laden, reports the AP.
Russian President Vladimir Putin, in his speech dedicated to the Day of the Russian Navy, recalled the threats that Russia is currently facing from a number of countries.