Authorities say a roadside bomb has hit a bus carrying Shi'ite pilgrims in southwestern Pakistan, killing at least 13 people.

The bus was traveling from Iran to Quetta, the capital of Baluchistan province when Thursday's blast occurred. The province has seen sectarian violence between majority-Sunni Muslims and minority Shi'ites.

The attack wounded at least 30 people.

Quetta police chief Mir Zubair said Thursday, “It's an open war. Security forces are ready to sacrifice themselves. We are trying our best to stop such attacks.”

A day earlier, a bomb exploded at a railway station in Baluchistan, killing at least five people and wounding more than 20 others in Sibi city.

Another blast killed at least eight Pakistani soldiers in the country's northwest early Thursday.

A roadside bomb exploded as a paramilitary convoy was passing through the town of Bara in the Khyber tribal agency.

No one claimed responsibility for the blast, but Pakistan's military has been battling Taliban and al-Qaida-linked militants in the country's northwestern tribal region.

The attack comes a day after the Pakistani Taliban released a video showing the heads of 17 Pakistani soldiers captured during a cross-border attack in the Upper Dir tribal agency.

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