Sikh pilgrims came from the northwestern city of Peshawar and returned home after a visit to the Nankana Sahib shrine in Sheikhupura. Officials said the injured were then taken to a hospital in Lahore, the capital of Punjab province, where two seriously injured died, bringing the death toll to 22.
Asghar Joya, a government official in Sheikhupura, said an initial assessment indicated that the bus driver had attempted to cross the railway as the train approached, but the bus skidded and got stuck. However, he said authorities are still investigating. He said authorities will provide a plane to transport the bodies to Peshawar, where dozens of relatives of the victims had gathered to mourn their loved ones.
Television footage showed the train and bus badly destroyed on the railroad tracks.
Sheikhupura resident Dilbir Singh said that the pilgrims, after visiting the shrine and before leaving for Peshawar, also visited the home of a relative whose family member had recently died.
Pakistani President Arif Ali and Prime Minister Imran Khan have issued statements expressing sadness and ordering local authorities to provide the best possible treatment for the injured.
Sikhs have several shrines of their religious leaders in Pakistan. One, from Sikh founder Guru Nanak, built after his death in the 16th century, is located in the Punjab village of Kartarpur, on the border with India.
Many Sikh holy places became part of Pakistan after the British divided the subcontinent into India and Pakistan in 1947 after two centuries of colonial rule. Links between rival nuclear-weapon neighbors deteriorated sharply after India revoked the semi-autonomous status of the disputed Kashmir region in early August.
Train accidents are frequent in Pakistan, mainly due to the lack of application of safety standards, a poorly maintained rail network and negligence of drivers. In February, a train crashed into a bus carrying passengers at an unmanned crossing in the Rohri district of southern Pakistan, killing 19 people and injuring 28 others.
Last November, a gas stove fire swept a train in Punjab, killing 74 people. Survivors of the time said it took almost 20 minutes for the train to stop; there were also conflicting reports on the condition of the train brakes.
Associated Press writer Asim Tanveer in Multan, Pakistan, contributed to this story.