13 bus passengers killed by militants in Pakistan August 6, 2013 -- Updated 1031 GMT (1831 HKT) Pakistani volunteers shift the body of a victim, killed by rebels outside a hospital in Quetta on August 6, 2013. Dozens of militants open fire on two buses, police say 13 passengers were taken to nearby mountains and killed No one has claimed responsibility for the attack Also in Balochistan, militants in police uniforms attack oil tankers and kill a security guard (CNN) -- Dozens of armed militants killed 13 bus passengers in Pakistan's militancy-hit Balochistan province during a pre-dawn attack Tuesday. More than 24 militants opened fire at two buses, forcing them to stop in Bolan district of Balochistan, police official Zubair Ahmed said. Ahmed said the militants took 13 of the passengers to the nearby mountains. Police later found the victims' bodies. "They had killed them one by one,"Ahmed said. He said the dead passengers included two security personnel. There was no immediate claim of responsibility for the attack. In the past, Balochistan separatists had killed laborers and passengers in the same area. He said the buses were headed from the province's capital, Quetta, to the Punjab region when they were attacked. Militants strike oil tankers Elsewhere in Balochistan province, armed militants dressed in police uniforms attacked two oil tankers Monday night. The tankers were carrying fuel for local security forces in the Mach area of Bolan district. Senior administration official Kashif Nabi said militants killed a security guard and injured another. The guards were protecting the oil tankers. Nabi said the attack partially damaged a tanker, and the attack was followed by a heavy exchange of gunfire between militants and security forces in the area.