British media reports that Anthony Joshua suffered minor injuries when the car he was travelling in collided with a stationary truck on a highway between Lagos and Ogun State.
The 36-year-old Briton has relatives in Sagamu, Ogun State.
Local police tell the BBC that Joshua is "fine" but that two people died. Joshua and other injured people have been taken to hospital.
According to a witness to the accident, the BBC reports, two cars were involved in the accident, a Lexus and a Mitsubishi. Joshua was reportedly sitting behind the driver in the Lexus, which was carrying two other people.
The two people who died were reportedly travelling in Joshua's car, according to AFP. The news agency also writes that according to a spokesman for the governor of Ogun State, "two male foreign nationals" died in the accident.
Nigeria's Federal Road Safety Authority said in a statement that the car Joshua and the victims were travelling in is suspected of driving faster than the speed limit and losing control while overtaking.
Just over a week ago, the former heavyweight world champion defeated influencer Jake Paul in a high-profile fight in Miami. Joshua is a two-time world champion who, before turning pro, won Olympic gold in the super heavyweight division in London in 2012.
