ISLAMABAD, Sept. 3 (Xinhua) -- At least 13 people were killed and 31 others injured when a blast went off in Pakistan's southwest Balochistan province on Tuesday, health and police officials said.

Confirming the casualties, Waseem Baig, media coordinator of the provincial health ministry, told Xinhua that the death toll might further rise as several among the injured are in critical condition.

The explosion occurred near a political gathering in the Shahwani Stadium area of the provincial capital city of Quetta, police sources told Xinhua.

According to the government officials, the explosion appeared to be a suicide bombing, saying an investigation has been launched into the incident to ascertain the exact nature of the cause and apprehend the perpetrators of the deadly attack.

After the attack, the law enforcement agencies and rescue teams reached the scene and the injured were taken to the hospital for treatment. The security forces have cordoned off the area and begun collecting evidence.

No group has claimed responsibility for the blast yet. ■