Several ropes supporting the slatted wooden bridge in Luang Prabang province snapped, tipping the children, a teacher and motorcyclist into the Xeng River below, according to the state-run Vientiane Times.
"Two children have died, 52 people have been rescued and three children are missing," the newspaper said.
The accident reportedly took place on Friday morning while the children were making their daily trek across the river to school.
The deputy governor of Viengkham district, Saykham Chanthoumma, told the Vientiane Times authorities were searching for the three remaining children by boat.
The official said the cables of the bridge, which was built in 2013, had not been checked for over a year.
Ruled by an authoritarian one-party government, landlocked Laos is one of Asia's poorest and least-developed countries.
Infrastructure and medical care in the rural nation is threadbare.
Its resource-rich economy has shot up from a low base in recent years following a flood of foreign investment, but the gains have not been evenly distributed.
Poverty remains rampant and the majority of its 6.8 million people work in agriculture.