A man has been arrested after a 16-year-old girl was stabbed to death on a rush-hour bus on one of Birmingham's busiest roads.
Christina Edkins was attacked on board the bus on Hagley Road while on her way to Leasowes High School in Halesowen.
Her head teacher Neil Shaw described her as a "bright and popular student" who was "much loved by staff and students".
A 22-year-old man was arrested nearby on suspicion of murder.
West Midlands Police said officers had spotted a man acting suspiciously who fitted the description of the suspect and was arrested after a short chase.
Det Supt Richard Baker said the teenager's family were "distressed and distraught".
Counsellors were also being brought in to support pupils and staff at Leasowes High School. BBC WM's James Boville said some were in tears as they left the school.
Mr Shaw said: "We are deeply saddened to hear this tragic news and our thoughts and hearts go out to her family and everyone who knew her."
Police said they would be checking Christina's profiles on social media websites as part of the investigation, but there was nothing to suggest she was being targeted.
Christina is understood to have boarded the bus minutes before the attack, which happened at about 07:40 GMT on Thursday.
Police said they were not looking for anyone else in connection with the stabbing. They added that there was nothing at this stage to suggest the attacker and Christina were known to each other.
The 22-year-old suspect was arrested near the Morrisons supermarket at Five Ways at about 12:30 GMT, following a city-wide manhunt.
Another man who was earlier detained in the city centre by police has since been released.
Det Supt Baker said officers were now analysing hours of CCTV footage, including some from on the bus.
He said he believed there were some passengers on board at the time of the attack who had not yet come forward.
Officers were patrolling buses and schools across the city on Thursday afternoon to help reassure people.
A specialist tanker was also brought in to empty drains as police continued their search of the area.
Detectives said the murder investigation was still in its "very early stages" and said they did not want to speculate on the motive.
The bus has been taken away from the scene, near the Five Ways junction of the Hagley Road, and the road has reopened.
A spokesman from National Express West Midlands said: "We can confirm that a tragic incident took place on a number 9 service 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."
Anyone with information can call police on 0800 096 0095.