The alarm was raised by the family of Ahmed Shamur, from Manor Park, in the early hours of Tuesday morning.
He was found dead at Gallions Reach DLR station just after 08:30 GMT and the Met has launched a murder investigation.
The teenage boy has died and his family and friends are devastated, Det Ch Insp Smith said. They want answers and they deserve all the help the public can give them.
Police said, a group of about 30 males carrying baseball bats was seen near the station in Beckton at about 19:50 GMT on Monday. The Met is investigating whether the sighting is linked to the fatal attack.