Armed men riding on motorcycles have killed eight people in an attack on a laundry in southwestern Pakistan, police say.

Four other people were injured after several men on motorcycles shot at a group inside the shop.

Saturday's attack took place in a commercial area of Quetta, the capital of southwestern Balochistan province.

Initial investigations indicated that the victims were "settlers", Iskandar Tareen, a senior police official, told the AFP news agency.

He was referring to people who have settled in Balochistan but come from other provinces of Pakistan.

Police official Salim Shahwani told the AP news agency that the victims were from Punjab province.

No one immediately claimed responsibility for the attack.

Police have launched an investigation to determine whether the attack was a hired killing, as such cases have been on the rise in the city.

Small separatist groups in impoverished Baluchistan also often target Pakistanis from other parts of the country.

The separatists want autonomy and a greater share of the money derived from the province's natural resources like gas and oil.

Many non-Baluch have left Balochistan in recent years.