South Yorkshire Police confirmed a 32-year-old Doncaster man has been arrested on suspicion of murder overnight, and is currently in police custody.
Four other people arrested on suspicion of murder – a 23-year-old man, a 20-year-old man, and two boys aged 16 and 17 – all remain in police custody.
Mr Williams died after suffering shotgun injuries to his neck and face on Wath Road, Mexborough, on Monday afternoon.
A 20-year-old man who was arrested on suspicion of assisting an offender has been released on bail pending further enquiries.
Although the cordon that was in place on Wath Road has now been lifted, other scenes remain in place as officers continue their investigation.
Police have urged anyone with information about Mr Williams’ death to call 101, quoting incident number 495 of 11 January.