A bus crash on a Nigerian highway on Saturday killed 21 athletes returning from a national sports tournament, with authorities saying the accident might have been the result of driver fatigue or excessive speed.The Federal Road Safety Corps (FRSC) said the afternoon crash, which did not involve other vehicles, “might have occurred as a result of fatigue and excessive speed” after a long overnight trip.The athletes were returning to Kano, in Nigeria’s north, from the 22nd National Sports Festival, held around 1,000 kilometres (620 miles) to the south in Ogun state.President Bola Tinubu had recently said the games, which included sports ranging from wheelchair basketball to traditional west African wrestling, represented “the unity, strength and resilience that define us as a nation”.Road accidents are common on Nigeria’s poorly maintained roads due largely to speeding and a disregard for traffic rules.Last year Nigeria recorded 9,570 road accidents that resulted in 5,421 deaths, according to FRSC data.