A bus carrying flood survivors from Karachi to their homes in Pakistan’s southern Sindh province caught fire on a highway, which led to the killing of at least 17 people, including 12 children, who were burned alive, a senior health official said on Thursday.

All 80 people on board the bus were flood victims who had taken shelter in Karachi after the deluge submerged their villages in Khairpur Nathan Shah in upper Sindh.

Monsoon floods, worsened by climate change, battered Pakistan for months, killing at least 1,700 people and wiping out the country’s infrastructure. The UN last week revised its flash appeal fivefold, from $160 million to $816 million, reflecting the magnitude of the disaster.

UN officials are concerned about health, nutrition, drinking water, shelter and food security for the vast swaths of the population who have lost their crops, homes and livestock.

“At least 17 bodies have been recovered from the bus. Of them, 12 are children, and two women and three men,” Qasim Soomro, Sindh parliamentary secretary of health, told Arab News.

“Another body, of a child, is suspected to still be in the bus but since the bodies have merged after being burned, we are not 100 percent sure.”

He said that the flood victims were all from the same community and had taken shelter in Karachi after flood waters had hit their villages.

The incident took place at night, near a police station in Nooriabad town.

Nooriabad Deputy Superintendent of Police Wajid Thaheem told media that the fire, which engulfed the entire bus, was believed to have been caused by a short circuit in the vehicle’s air conditioner.