Police in Nigeria say four suspects have been arrested so far in connection with the killing of a musical sound engineer by a mob in Lagos.

The authorities say a number of other suspects are being tracked down.

The killing of David Sunday Imoh has sparked outrage with the hashtag #JusticeForDave trending on social media in Nigeria.

The exact circumstances leading to his death are still unclear.

But local media reports suggest the 38-year-old was beaten to death and his body set alight by a mob following a heated argument with a commercial motorbike rider over pay.

The violence happened in Lagos' Lekki area last Thursday.

A police spokesperson told the BBC that a criminal investigation was underway.

This is happening at a time when Nigerians continue to react to the killing of a female student in the northern city of Sokoto after she was accused of blasphemy against Islam.

Human rights campaigners say the frequent cases of mob violence in Africa’s most populous country are fuelled by impunity and a lack of confidence in the criminal justice system.