Two more people have been arrested following the killing of David Adegbite who was shot dead in Barking.
The former Havering College student, 18, was gunned down as he cycled through an east London estate on the evening of Sunday, March 19 as children played nearby.
He was ambushed by a gang who shot him in the head.
On Wednesday police said they have arrested two more men.
A 22-year-old man was arrested on Monday, March 27 in connection with the murder and has been bailed until a date in late May.
On Tuesday police arrested another man, aged 26, on suspicion of assisting an offender. He remains in custody at an east London police station.
DCI Jamie Piscopo leads the investigation. He said: "I am continuing to appeal for anyone who was in the area of St Ann's at around the time of David's murder and who saw anything suspicious to contact police.
"My team continue to work to establish the series of events which led to this murder and, at this early stage, retain an open mind as to the motive."
A 20-year-old man who was already arrested in connection with the murder has been bailed to a date in May.
Anyone who witnessed the incident or has any information is asked to contact the incident room on 020 8345 3715 or call Crimestoppers, anonymously, on 0800 555 111.