DERA ISMAIL KHAN, Pakistan - Suspected Islamist militants blew up a police vehicle in northwestern Pakistan on Sunday, killing seven people, including three policeman and three paramilitary troops, officials said.
The vehicle was on a routine patrol on the outskirts of the town of Dera Ismail Khan when the bomb apparently planted in a dusty road exploded as it passed over.
Dera Ismail Khan is close to the Waziristan tribal region where security forces have been battling al Qaeda-linked militants and their local supporters over the past two years.
"It was a remote-controlled bomb," Daar Ali Khattak, District Police Officer, told reporters.
Khattak said a passerby was among the dead and hospital officials said five people were wounded, including two women.
No one claimed responsibility for the attack but Interior Minister Aftab Ahmed Khan Sherpao said Islamist militants were likely behind the blast.
A few hours later, a second bomb went off near the site of the first blast. A wall of a nearby government building collapsed, but there were no casualties, residents said.
A third bomb went off near a police checkpost in another part of the town but caused no casualties, police said.
"It appears to be the spillover of what is going on in Waziristan," Sherpao told Reuters.
Nearly 200 pro-Taleban militants have been killed in clashes with security forces in the North Waziristan tribal region this month. Many al Qaeda fighters and their Taleban supporters fled to the semi-autonomous tribal belt after US and Afghan opposition forces ousted the Taleban in Afghanistan in 2001.
Pakistani security forces have been trying to clear foreign militants from the area and subdue their Pakistani allies since 2004.
Khattak said security had been beefed up in Dera Ismail Khan and nearby Tank town over concerns of militant attacks. "We consider these towns as hot targets of the militants," he said.
Police in Tank last week issued a warning to local authorities that militants could target government offices, buildings and vehicles in retaliation for the military's crackdown in the tribal areas.
Pakistan's tribal belt and areas on the Afghan side of the long border are dominated by ethnic Pashtuns.
Many tribesmen sympathise with the Taleban, also Pashtuns, and al Qaeda leader Osama bin Laden and his deputy Ayman al-Zawahri are believed to be hiding in the region.
Afghan officials have long complained that militants use Pakistani territory as a springboard for launching attacks inside Afghanistan.
Pakistan, a key ally in the US-led "war on terrorism", says it is doing all it can to stem cross-border movement of the militants and has urged Afghan authorities to do more on their side of the porous border.