The attack took place in the neighborhood of Clifton in Karachi, the capital of southern Sindh province, senior police officer Abdul Khaliq Sheikh said. The bomb badly damaged several vehicles and a nearby multi-story building, he said.
Pakistani television stations showed the blast scene littered with broken glass and debris. Five of the wounded were in critical condition, said Dr. Seemi Jamali at the city's Jinnah Hospital.
No one claimed responsibility, but the bombing was the latest in a series of gun and bomb attacks as the government of Prime Minister Nawaz Sharif tries to reach a peace deal with the Pakistani Taliban to end the violence that has killed thousands of people in recent years.
The attack also took place a day after a bomb targeting prominent police officer Shafiq Tanoli exploded in another area of Karachi, killing the officer and three others. The slain officer, who had survived several attempts on his life, was targeted for his active campaigning against terrorists.
Provincial Information Minister Sharjeel Memon told journalists that the bombers wanted to target government vehicles passing through the area. At least three vehicles bearing government plates were damaged in the bombing, but it was not unclear whether any government official was wounded, he said.
Karachi is a hiding place for local and foreign militants. Clashes between heavily armed ethnic and political groups are common there.