(CNN) -- Seven people were killed and 20 injured Wednesday night when a bomb exploded in a crowded railway station tea shop in southwest Pakistan, a government official told CNN.
Separatist Baloch militants are suspected in the attack, which apparently targeted ethnic Punjabis traveling as train passengers through the Balochistan province, government official Shahid Saleem said.
The attack took place in the town of Sibi, about 150 kilometers (95 miles) southeast of the provincial capital of Quetta.
The Balochistan province has Pakistan's richest supplies of minerals and natural resources, but its population ranks among some of Pakistan's poorest. For decades it has been plagued by sectarian violence and separatist Baloch militant groups who demand political autonomy and a greater share of profits from the province's natural wealth.
The Pakistani military has responded with severe crackdowns against the separatist groups. Human rights groups have accused the army of extrajudicial killings and abductions during their operations in Balochistan.
Tens of thousands of people have been killed in sectarian violence and government rebellions in Balochistan since the province saw its first uprising in the 1970s.
CNN's Michael Martinez contributed to this report.