He was the 17yo son of Rwandan immigrants as reported in this thread.

https://greatawakening.win/p/17txMWcZM3/watch-how-many-more-children-pri/

Sadly 3 children ages 6, 7 and 9 are now dead from this horrible attack.

A third child has died after a knife attack in Southport, England, and five children and two adults remain in a critical condition, the police said on Tuesday. A 9-year-old girl died in the hospital in the early hours of Tuesday, the police said in a statement, while two other girls, age 6 and 7, died on Monday as a result of their injuries. The attack, which the local police chief, Serena Kennedy, described as “ferocious,” took place at a Taylor Swift-themed dance class for children ages 6 to 11. A 17-year-old boy was arrested and is being questioned by the police.