Bolivian authorities say four people were killed and more than 60 injured when an overloaded metal footbridge collapsed onto a group of musicians marching in the opening parade of Carnival in the highlands city of Oruro.

Interior Minister Carlos Romero said three of the dead were musicians.

Dozens were on the bridge Saturday when it collapsed and the normally festive, even raucous, parade of colourfully clad musicians and dancers became a funereal march.

The four-day annual event is Bolivia's most celebrated festival, drawing at least 20,000 musicians and dancers, and tens of thousands more tourists to the regional capital.