A passenger train hit a school bus at an unmanned railway crossing in Pakistan’s east amid dense fog on Wednesday, killing at least eight children and the bus driver, police said.

Twelve children also were injured in the collision near the Punjab province town of Mian Channu, and some were in serious condition, police official Mohammed Farooq said. There were no known casualties on the passenger train.

Parts of Pakistan are currently under the grip of heavy fog which has caused several road accidents.

Low visibility also has forced authorities to occasionally suspend traffic on the country’s main highway linking the capital, Islamabad, with the eastern city of Lahore and other towns.

The fog also has disrupted airline schedules.

Train accidents already are common in Pakistan because of its antiquated railway system. Railway crossings often are poorly maintained, and are sometimes unmanned or lack gates in various parts of the country.

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