The accident occurred on the busy motorway near Hafizabad when 12 cars crashed into each other and collided with a bus due to heavy fog, they said.
"I can confirm that 13 people have been killed," senior police official Sardar Gul said.
The injured were shifted to nearby hospitals.
An official of motorway police said that most of those killed were going to annual religious congregation of Tableeghi Jamaat which is being held at Raiwind near Lahore.