QUETTA: At least four people were killed and 18 others wounded in an explosion in Balochistan's Sibi district on Sunday.

Unknown persons had planted a bomb on a motorcycle, parked on the road side, in Chakar Khan road area of Sibi which went off with a huge bang, Anwar Khetran, the District Police Officer (DPO) Sibi told DawnNews.

He further said that the nearby buildings and shops were also damaged in the explosion and added that all the blast victims were civilians.

"The target of blast is yet to be confirmed," Khetran said.

Security and rescue teams reached the blast site. Security personnel cordoned off the area as a probe into the incident went underway.

Rescue sources said that the victims were shifted to Civil Hospital, Sibi where an emergency was imposed to treat the injured.

The condition of three wounded was reported as critical where as five victims had been treated for minor injuries.

Shopkeepers pulled down their shutters after the blast as fear and panic prevailed in the city.

There was no immediate claim of responsibility for the blast.

Balochistan has been under the grip of sectarian violence and attacks of Baloch separatists and unknown elements since more than a decade.

Scores of people have lost their lives in sectarian suicide bombings and target killings.