The road accident occurred overnight in Jamshoro district in southern Sindh province, city police chief Saddique Changra told reporters.
Hospital officials said some of the injured were in critical condition.
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According to local media, the accident happened as dozens of laborers were returning to their homes in Sindh's Badin district after harvesting wheat in the southwestern province of Balochistan.
Road accidents are common in Pakistan, where highways and roads are poorly maintained and traffic laws are widely ignored.