QUETTA, Pakistan — Police in Pakistan say gunmen riding on motorcycles shot and killed a police officer guarding minority Shiites in the southwestern city of Quetta.

Abdur Razzaq Cheema, police chief in Quetta, said another police officer was wounded in Wednesday’s attack.

No one immediately claimed responsibility, but Sunni extremists have targeted Pakistan’s Shiite minority in past attacks, while Baluch separatists in the area have attacked security forces.