Indian officials say an overcrowded flatbed trailer pulled by a tractor has overturned into a pond, killing at least 40 people in the northern state of Utter Pradesh.

Police say most of the victims drowned at the site of the accident in the Ballia district, south of the state capital, Lucknow.

Authorities say more than 50 people had crammed onto the trailer Monday to attend a religious festival.

The World Health Organization says India has the highest annual number of road deaths in the world.