Roadside bomb hits police vehicle in Pakistan, wounding 19

A Pakistani police official says a roadside bomb has struck a vehicle carrying police in the country's northwest, wounding four officers and 15 passers-by.

Local police official Mohammad Nawaz says Wednesday's attack took place in the city of Dera Ismail Khan, a gateway to Pakistan's troubled tribal region bordering Afghanistan.

No one immediately claimed responsibility for the bombing. Pakistan's army has carried out several operations against local and foreign militants in the country's tribal regions in recent years.

The army says it has cleared over 90 percent of the region from insurgents, who once had a strong presence there.