A bus packed with passengers caught fire after colliding with a truck carrying a flammable liquid in southern Pakistan (search) early Friday, killing at least 31 people, police said.

At least 11 people were injured, some of them critically, when the bus hit the truck on a slippery road near Saeed Abad, a town about 230 kilometers (142 miles) northeast of Karachi, said Faisal Mohammed, a police inspector.

He said rescue teams transported charred bodies and the injured to hospitals. The bus was completely gutted, he said

Mohammed said the truck was carrying synthetic spirit, a flammable liquid used by medicine companies and chemical factories in Pakistan. He blamed the accident on poor visibility due to heavy fog and rain.

Another police official, Sikandar Ali, said the dead included 13 children, nine women and nine men. As many as 16 of the dead belonged to two Karachi families, who were retuning to their city after attending a wedding. The bus driver also died in the accident.

Road accidents are common in Pakistan, where many roads are poorly maintained and drivers often are not properly trained and frequently disregard rules.

The latest accident came less than a week after a speeding bus plunged into a deep ravine in eastern Pakistan, killing 18 people and injuring 39 others.

Karachi is the capital of Pakistan's southern Sindh province.