Two further arrests have been made over the death of a 16-year-old boy - fatally stabbed on board a bus in east London.
Amateur boxer Tyler Hurley died in hospital after being stabbed on the 173 bus in High Road, Chadwell Heath, on March 14.
A man and woman have been arrested in connection with the teenager’s death but police are not providing any more information about them at this point for “operational reasons”.
Police previously charged Carlton Tanueh, 18, of no fixed address, with murder last week.
Mr Tanueh, who is also charged with two counts of being in possession of an offensive weapon, appeared at Barkingside Magistrates Court on March 16.
He is due to appear at the Old Bailey at a future date.
Police were called to a 173 bus on Chadwell Heath High Road, near Whalebone Lane, Barking and Dagenham, at 3.55pm on March 14, where they found Tyler with a stab wound.
He was rushed to hospital by paramedics, and was declared to be in a “life-threatening” condition.
He sadly died the next day.
Det Ch Insp Mark Rogers said: "This crime has shocked the community, particularly Tyler’s fellow pupils and teachers at his school.
“Our investigation remains ongoing and we have spoken to a number of people, but I know there are others who have yet to come forward and tell us what they know.
“This incident took place on a bus in broad daylight and I am sure there are many people who were horrified at what unfolded.
"I understand how daunting it can be, but if you have any information no matter how small this might be, then we need to hear from you.
“We know this is a big ask of you, particularly to the young people in our community.
“Be assured, if you come forward with information, there will be measures put in place to protect you.
"To come forward, you could speak to a trusted person like a teacher, social worker, or a youth worker.
“Or you can tell us what you know anonymously using Crimestoppers, an independent charity.
“Your computer and mobile phone IP addresses cannot be tracked or saved.
“Your anonymity is guaranteed. Call 0800 555 111 or online www.crimestoppers-uk.org
"You can contact the Met Call Centre on 101 quoting CAD 4741/14Mar. This can be done anonymously.
"What matters most is that you make the call."
Det Ch Supt Paul Trevers, head of policing for Barking and Dagenham, said: "My officers are out patrolling the area following this horrific incident.
“We are determined to do everything we can to support our colleagues in Specialist Crime as they work to bring justice to young Tyler’s family.
"Police and communities must work together to stop violent crime, and that means we need people to speak to us.
“Please be assured that there are anonymous methods such as Crimestoppers, but also that if you do want to speak to us in person, it will be in the very strictest of confidence."
Any witnesses or anyone with information about the incident is asked to call the incident room on 0208 345 3715.
Alternatively, call 101 quoting CAD 4741/14Mar or contact the independent charity Crimestoppers anonymously on 0800 555 111