west midlands police
The incident has been referred to the Independent Office for Police Conduct, who will review body-worn video.
The force later removed the killer's name from its advertising.
Five properties were targeted in dawn searches.
They are both in hospital.
"West Midlands Police are being hit more than twice as hard as the likes of leafy Surrey."
Detectives are hunting the attacker.
Four other teenagers were arrested.
Staple will play this afternoon with a message about knife crime.
The man was detained in the Sparkhill area of Birmingham.