Police have hailed the bravery of teachers, parents and pupils who intervened as a girl was repeatedly stabbed outside her school.
Chloe West, 14, suffered serious injuries to her upper body and face in the attack.
She was airlifted to hospital from the scene at Ridgewood High School in the Wollaston area of Stourbridge.
Police said Chloe's attacker confronted her as she approached the school gates with a friend.
A number of people came to her aid, including staff, pupils and parents.
An 18-year-old man has been arrested and is being questioned on suspicion of attempted murder.
Police said he is known to Chloe. Local reports suggest he is her ex-boyfriend.
Detectives paid tribute to the bravery of those who helped Chloe and tackled the suspect.
One teacher is believed to have sat on him while they waited for the police.
West Midlands Police Superintendent Stuart Johnson commended their bravery in what he described would have been a "very frightening scene".
"I would like to pay tribute to some very brave individuals who, without too much thought for their own safety, intervened," he said.
"They showed tremendous bravery in intervening and detaining the suspect. They clearly prevented far more serious injuries to Chloe."
Chloe is conscious and her injuries are no longer thought to be life-threatening.
She is expected to undergo surgery at Birmingham Children's Hospital.
Chief Inspector Mark Bramwell, from Dudley police, said: "We are in the very early stages of this inquiry.
"However, we do believe this to be an isolated incident and wish to reassure other pupils and parents that there are not any known risks to any other individuals.
"Local officers and detectives will be at the scene today to speak to those with concerns, or information they wish to pass on to the investigation team.
"A man is currently in police custody and will be questioned in due course."
The suspect also sustained hand injuries and has been treated prior to any questioning by police officers.
Witnesses told how they saw a man drive up and leap out of a burgundy Volkswagon Polo armed with a knife.
The secondary school has been closed with parents called to collect their children. It is expected to re-open on Monday.
The school would not comment on the incident when contacted by Sky News.
Any witnesses, or anyone with information, is urged to contact Dudley Police on 0345 113 5000.