A police spokesman says gunmen in twin attacks minutes apart have shot and killed four policemen in southwestern Pakistan before escaping.

Spokesman Shahzada Farhat says the attacks took place late Tuesday in Quetta, the capital of impoverished Baluchistan province. No one has immediately claimed responsibility and Farhat says they are investigating who was behind the latest "acts of terrorism."

Baluchistan is Pakistan's largest province and the scene of low-scale insurgency for the past several years.

Small separatists groups in the region often attack police and security forces to pressure the government to get more wealth from resources like natural gas and oil extracted from the province.