Fighting between armed Sunni and Shiite groups in northwestern Pakistan killed at least 33 people and injured 25 others, a senior police officer from the region said Saturday.

The overnight violence was the latest to rock Kurram, a district in Khyber Pakhtunkhwa province, and comes days after a deadly gun ambush killed 42 people.

Shiite Muslims make up about 15% of the 240 million people in Sunni-majority Pakistan, which has a history of sectarian animosity between the communities.

Gunmen kill 42 Shiites in northwest Pakistan

Although the two groups generally live together peacefully, tensions remain, especially in Kurram.

The senior police officer said armed men in Bagan and Bacha Kot torched shops, houses and government property.

Intense gunfire was ongoing between the Alizai and Bagan tribes in the Lower Kurram area.

“Educational institutions in Kurram are closed due to the severe tension. Both sides are targeting each other with heavy and automatic weapons,” said the officer, who spoke anonymously because he was not authorized to speak to the media.

Videos shared with The Associated Press showed a market engulfed by fire and orange flames piercing the night sky. Gunfire can also be heard.

The location of Thursday’s attack was also targeted by armed men, who marched on the area.

A suicide car bombing at a security post in northwestern Pakistan has killed 12 troops

Survivors of the gun ambush said assailants emerged from a vehicle and sprayed buses and cars with bullets. Nobody has claimed responsibility for the attack and police have not identified a motive.

Dozens of people from the district’s Sunni and Shiite communities have been killed since July, when a land dispute erupted in Kurram that later turned into general sectarian violence.