Scotland Yard
Ahmed Munajed is due to appear at Westminster Magistrates' Court on Wednesday.
Luciano Newman was just eight months old.
An 18-year-old man was held on Saturday morning.
Scotland Yard is appealing for information about Ossama Hamed, 25, and 23-year-old Nor Aden Hamada.
Police were called to Bickley Road on Tuesday.
Scotland Yard is investigating whether any criminal offence was committed.
The teenager had been detained on suspicion of assaulting a police officer.
The incident took place at Gants Hill roundabout in Redbridge, east London, on Friday evening.
A 26-year-old man is being held on suspicion of murder at a central London police station, officers said.