At least two security personnel were killed Sunday evening when some unknown gunmen opened fire at a security check-post in Pakistan\'s southwestern provincial capital of Quetta, local media reported. According to the reports, the incident took place when personnel of Frontier Constabulary (FC) stopped a vehicle for search at Burma Hotel check-post at the Saryab Road of Quetta. Two passengers in the vehicle took out their automatic guns and sprayed bullets at the FC personnel, killing two of them on spot. Other security personnel at the checkpoint retaliated with intense firing that killed one of the attackers while his companion managed to flee from the scene. Rescue teams, police and security personnel reached the site and shifted the bodies to the hospital. Police and security teams cordoned off the area and launched a search operation to arrest the runaway assailant but made no avail. No group or militant organization claimed responsibility for the incident yet.