An explosion hit a bus travelling on a highway between Herat and Kandahar in western Afghanistan on Wednesday.
At least 34 passengers, including children were killed and 17 were injured.
The Taliban and Islamic State fighters have doubled their attacks on Afghan forces and civilians.
Police spokesperson Mohibullah Mohib said, the bomb was planted by the Taliban insurgents to target Afghan and foreign security forces.
There was no claim for the attack by Taliban.
Afghan government officials say, the number attacks is rising and more and more civilians and forces are dying in the attacks.
They said, the Taliban now control more territory now than they controlled 18 years ago the Taliban government was toppled by the U.S. forces.