Officials say a roadside bomb has exploded near a security convoy in northwestern Pakistan, killing two soldiers and 15 others. A police official says the attack happened Thursday in Dera Ismail Khan, a former stronghold of the Pakistani Taliban in Khyber Pakhtunkhwa province bordering Afghanistan. No group immediately claimed responsibility. Similar attacks in the past have been claimed by the Pakistani Taliban, which is known as Tehrik-e-Taliban Pakistan and is an ally of neighboring Afghanistan’s Taliban rulers.