The 14-year-old is arrested on suspicion of murder after another teenager dies following a stabbing.
A 14-year-old boy has died following a stabbing in Gateshead.
The teenager, who has not been named, was seriously injured in the Aycliffe Crescent area of the Springwell Estate at about 20:00 BST on Monday.
Another 14-year-old boy has been arrested on suspicion of murder and a girl, 13, has been detained on suspicion of assisting an offender.
The injured boy was taken to hospital but died in the early hours of Tuesday, Northumbria Police said.
Ch Supt Helena Barron, of Northumbria Police, said: “A teenage boy has sadly died and his family have been left devastated beyond belief.
“Our thoughts are very much with his loved ones at this time and we are supporting them in every way we can.
“We are determined to find out exactly what happened and a full investigation is ongoing into the circumstances surrounding this tragic incident.”
She asked the public not to speculate online about the investigation, adding: “What might seem like an innocent post on social media could in reality disrupt an on-going investigation and cause further upset to the family of the victim.”
The boy and girl who were arrested remain in police custody.
Northumbria Police and Crime Commissioner Kim McGuinness said the death was “devastating”, adding: “My thoughts are with the victim’s family who will be experiencing unimaginable pain.
“This should never have happened and it now sits with our police to carry out extensive inquiries to establish the full circumstances that have led to the senseless loss of a young life.”