A group of athletes was returning home from Nigeria's National Sports Festival when their bus veered off a bridge.

At least 21 athletes were killed on Saturday after the bus they were traveling on drove off a bridge in the northern Nigerian state of Kano, the state governor said.

The athletes were returning home from the National Sports Festival that they had been participating in for the previous week in Ogun state, in the country's southwest.

Governor Abba Kabir Yusuf said that the driver of the bus appeared to lose control while crossing over the Chiromawa Bridge on the Kano-Zaria expressway.

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Several other passengers were injured in the crash.

The Federal Road Safety Corps (FRSC) said the accident may have been the result of "fatigue and excessive speed" following a long overnight journey.

Footage after the accident showed a mangled bus underneath a bridge.

Athletes returning from Nigeria's National Sports Festival

More than 30 passengers were on board at the time. The survivors were taken to a local hospital for treatment.

Monday has been declared a day of mourning in Kano. The deputy governor, Aminu Gwarzu, said that the families of the victims would be given 1 million naira (around $630, €550) as well as food supplies.

The athletes had been representing their state in the festival which takes place every two years, allowing competitors from Nigeria's 35 states to take part in multi-sports events, including wheelchair basketball and traditional west African wrestling.

President Bola Tinubu said of the festival that it represented "the unity, strength and resilience that define us as a nation."

Poor road conditions and a casual enforcement of traffic rules make road accidents a common occurrence in Nigeria.

The FRSC recorded 9,570 road accidents and 5,421 deaths last year.

Alex Berry with AP, AFP

Edited by: Darko Janjevic