QUETTA, Pakistan (AP) -- A bomb ripped through a railway car parked at a station in southwestern Pakistan, killing at least 13 people and sending flames and smoke billowing into the air, officials said.
The explosion in the town of Sibi also wounded 35 people, said district police chief Gulam Abbas Tarar. He put the death toll at 13 while another official, Suhail-ur-Rehman, the deputy commissioner of the district, said 14 people were killed.
The Pakistani television stations showed images of the burning car, with flames shooting out of the windows and smoke billowing into the sky.
Sibi is in Baluchistan province, Pakistan's largest region. The train was going from Quetta, the capital of Baluchistan, to Rawalpindi, which is next to the capital of Islamabad. Sibi is located about 150 kilometers (90 miles) east of Quetta.
The bomb went off after it reached the Sibi station and passengers were boarding and disembarking from the cars, officials said.
There was no immediate claim of responsibility. Pakistan has been battling Baluch separatists in the area as well as sectarian groups.
Federal Minister for Railways Saad Rafiq told Geo TV that initial reports suggest a woman left explosives on the train car and then got off the train when it arrived at the station. The deputy commissioner said it might have been concealed in someone's luggage but emphasized that authorities were still investigating.
Baluchistan has been plagued by violence from various factions for years.
Rafiq said the blast could have been retribution for a Pakistani military operation on Monday that left at least 30 militants dead.
The paramilitary Frontier Corps said they killed the militants in Khuzdar, a mountainous region southeast of the Baluch capital, during an operation targeting their hideouts. The Frontier Corps said 10 of its troops were wounded in the operation.