QUETTA, Pakistan (AP) - A bomb exploded on a busy street in the southwestern Pakistan city of Quetta on Friday, killing a 4-year old girl and wounding 11 other people.

The bomb was rigged to a motorcycle and it exploded outside a commercial bank, said Raja Mohammed Ishtiaq, a Quetta police officer. There was no immediate claim of responsibility.

Four of the wounded were traffic police on duty nearby, and others were passers-by, said Mohammed Khalid, another police officer.

The wreckage of the motorcycle - to which Ishtiaq said the bomb was attached - lay scattered on the roadside. The windows of cars parked in front of the bank were damaged.

Quetta is the capital of southwestern Baluchistan province, where authorities have blamed armed tribesmen for bombings and attacks against the government.

Ethnic Baluch tribesmen are waging a low-level insurgency to press for greater provincial autonomy and control over natural resources in Baluchistan.