Islamabad, May 30 (RHC)-- A group of heavily armed terrorists have shot dead at least 20 passengers and injured several others after taking them hostage from two buses in the troubled southwestern Pakistan.

This came after more than two dozen assailants attacked the buses in the Mastung district of the southwestern Balochistan province on Friday evening.

Local security officials say the terrorists abducted several passengers and then shot at least 20 of them dead in execution-style murders. Meanwhile, Provincial Information Minister Abdur Rahim Ziaratwal said on Friday night that the gunmen still hold some passengers and that the operation to recover them is still underway.

No group or individual has yet claimed responsibility for the deadly attack, but pro-Taliban militants have been blamed for such attacks in the past. The latest attack occurred as several buses carrying Shia Muslim pilgrims have been attacked by militants in recent months across the troubled province which borders Iran.

In another bus attack on May 13th, pistol-wielding gunmen massacred nearly 50 Ismaili Shia Muslims in the southern port city of Karachi. The attack was claimed by the pro-Taliban Jundullah terrorists, which had previously allied themselves to the ISIL Takfiri group.

Thousands of Pakistanis have lost their lives in bombings and other militant attacks since 2001, when Pakistan entered an alliance with the United States in the so-called war on terror. Thousands more have been displaced and are homeless.