A bridge collapsed under an overloaded truck in Guinea, throwing scores of passengers into a river and killing at least 70, the West African country's state radio reported Wednesday.

The truck was ferrying merchandise and people back from a local market near the southeastern town of Gueckedou when the accident occurred Sunday, state-run RTG radio reported.

The 50-year-old rock and cement bridge collapsed as the truck was crossing, tipping the vehicle and sending people as well as bags of cement and sacks of rice crashing into the river. Many of the dead drowned, trapped under the merchandise, RTG said.

At least 20 people were injured and were taken to hospital, the radio station reported. Some later died of their injuries. The death toll rose from 65 overnight to 70 Wednesday morning, the radio said, citing hospital sources.

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Hospital officials could not be immediately reached for comment.

Guinea, a country of 10 million on Africa's West Coast, is deeply impoverished despite having half the world's supply of bauxite — the raw material used to make aluminum — as well as iron ore, gold and diamonds.

In rural areas where buses are rare, large open-backed trucks are often a main form of transport — carrying sacks of grain, sheep, bicycles and people between villages. Trucks are often piled high with merchandise, and then passengers climb on top, or hang onto the sides of the vehicle.