Detectives investigating an incident in Upminster have arrested two more men.
A man, aged in his 30s , was arrested on suspicion of aggravated burglary.
A second man, also aged in his 30s , was arrested on suspicion of conspiracy to commit burglary and assisting an offender.
Both remain in police custody.
Police were called at 21:30hrs on Friday, 1 May, to an address on Kerry Drive in Upminster.
Officers attended along with the London Ambulance Service (LAS) and found two people at the address suffering injuries.
An 11-year-old boy had sustained a gunshot injury. He remains in hospital in a serious but stable condition.
A man, aged in his 40s, had sustained lacerations to his head. The condition of the man has been assessed as not life-threatening or life-changing.
Detective Inspector Matthew Webb, leading the investigation, said: “Enquiries into the circumstances of what happened continue and we are grateful to the public who have come forward so far. Anyone with any information is asked to contact police or, to remain anonymous, Crimestoppers.”
A 26-year-old man has been charged in connection with the investigation. He is due to appear at Barkingside Magistrates’ Court on Wednesday, 6 May.