At least four policemen were killed when some unknown gunmen opened fire at their vehicle in southwest Pakistan's Balochistan province on Thursday, local media reported. Dunya TV said that the police vehicle came under attack on routine patrol in Shahenshah area of Dera Murad Jamali district. The attackers fled the scene following the attack while the rescue teams shifted bodies to a nearby hospital for autopsy. No group has claimed responsibility for the attack yet. This was the second attack on police Thursday and fourth of its kind over the last three days. Earlier Thursday, four people including a senior police official were killed in a suicide blast in the country's southern port city of Karachi.