Gunmen have attacked two teams of polio workers in southern Pakistan, killing three members of the teams and wounding a fourth before fleeing, Pakistani police said today.
Police official Pir Mohammad Shah said two women and a man were killed in the attacks in Karachi, the capital of southern Sindh province.
Health official Zafar Ejaz said the vaccination campaign was cancelled following the attacks.
No group has claimed responsibility but Pakistani militants have killed several polio workers and police protecting them in Karachi and elsewhere in recent months.
Pakistan is one of only three countries where the polio virus is still endemic.
Militants oppose vaccination against polio and consider such campaigns a cover for spying. They also claim the vaccine is intended to make Muslim boys sterile.