The bomb went off at Kuchlak Bazar this morning near the venue of a rally organised by the ANP, which is part of the ruling coalition at the centre.
Malik Qasim, provincial vice-president of the Pashtoon Students Federationthat is affiliated to the ANP, and an eight-year-old girl were among the dead, officials and witnesses said.
Aurangzeb Kasi, head of the Balochistan chapter of the ANP, and his wife were among the injured. Officials said they were out of danger.
Witnesses said the blast was followed by firing. It could not immediately be ascertained who was responsible for the firing. Officials said the bomb was attached to a bicycle.
Footage on television showed several vehicles and nearby buildings were destroyed by the blast. The cars were hit by pellets packed into the bomb. Shoes and slippers law strewn at the venue of the rally.
No group claimed responsibility for the blast, which occurred hours before an official visit by Prime Minister Raja Pervez Ashraf to Quetta, the capital of Balochistan province.