Gunmen opened fire on passenger vehicles carrying Shiite Muslim civilians in restive northwest Pakistan on Thursday, killing at least 28 people, including six women, and wounding 30 others in one of the deadliest such attacks in recent years in the region, police said. The attack happened in Kurram, a district in the northwestern Khyber Pakhtunkhwa province where sectarian clashes between majority Sunni Muslims and minority Shiites have killed dozens of people in recent months. No one has claimed responsibility. The latest violence came a week after authorities reopened a key highway in the region after keeping it closed for weeks following deadly clashes. Local police official Azmat Ali said several vehicles carrying passengers were traveling in a convoy from the city of Parachinar to Peshawar, the capital of Khyber Pakhtunkhwa, when gunmen opened fire. He said the dead included six woman, and least 10 passengers were in a critical condition at a hospital. Pakistan's President As