Boy's mother works at local schoolpublished at 13:49 British Summer Time 1 May
Although the 14-year-old boy has been named locally as Daniel Anjorin, the Met Police has not confirmed the name.
Earlier, the school where the boy's mother works released a statement.
Holy Family Catholic School, in Waltham Forest, said "it is with great sadness that I share with you the news of the death of the child of one of our staff members.
"Mrs Anjorin's son was taken from this life suddenly this morning on his way to school. Please keep Mrs Anjorin, her husband and their other children in your prayers."
The BBC understands that Daniel was a pupil at Bancroft's School.