The 16-year-old schoolgirl who died after being stabbed on a bus in Birmingham has been named as Christina Edkins.
West Midlands Police also said a 22-year-old man has been arrested on suspicion of murder following the morning rush-hour stabbing on the A456 Hagley Road in Five Ways in the centre of Birmingham.
Police say spotted a man acting suspiciously who fitted the description of the suspect wanted in connection with the 16-year-old's murder. Following a short footchase the man was arrested and is being held on suspicion of murder.
A man previously arrested on Lower Temple Street in the centre of Birmingham was later released.
Christina was a pupil at Leasowes High School in Halesowen. Police say her family are being supported by specially trained family liaison officers.
The headteacher at Christina's school, Neil Shaw said: "Christina was a bright and popular student much loved by staff and students alike. We are deeply saddened to hear this tragic news and our thoughts and hearts go out to her family and everyone who knew her.
"The school is working closely with the police and a team of counsellors to provide support to our pupils and staff."
Det supt Richard Baker from Force CID said: "This is a tragic case and the victim's family are devastated.
"We are still anxious to hear from anyone with information or who may have witnessed the incident this morning to speak to us via the dedicated hotline 0800 096 0095.
"There will be a high police presence across the city this afternoon following this morning's tragedy particularly on buses and in schools in the area to provide reassurance to local people."
A National Express West Midlands Travel spokesman said: "We can confirm that a tragic incident took place on a number nine service on the Hagley Road this morning.
"Our thoughts and condolences are with the family of the person involved and we will offer all possible support to the police in their investigation into the matter."
Witnesses are being urged to call the police on 101 or Crimestoppers on 0800 555 111.