A man has been arrested after two men were stabbed to death in Birmingham city centre during Friday evening rush hour last.
There are "potentially hundreds of witnesses" who either saw the stabbings or the offender leaving the scene, according to West Midlands police.
A large number of officers went to the scene after receiving reports of the stabbings just before 6pm.
One victim is understood to have been stabbed outside Sainsbury's in Martineau Place while the other was found slumped near Boots in Union Street also having suffered fatal injuries, the force said.
First aid was given to the men – believed to be in their 40s – but both were pronounced dead at the scene.
A man was arrested in New Street, near the Odeon Cinema, minutes after the stabbings, but the police say they are keen to hear from anyone who was in the area at the time.
Inspector David Keen of West Midlands police said: "Two men have suffered fatal injuries – these have been inflicted in the heart of the city at a busy time when workers and shoppers would be heading home.
"There are potentially hundreds of witnesses, either people who saw the stabbings or the offender leaving the scene, and I'd urge people to get in touch immediately – they could have vital information.
"A large police presence was quickly on the scene and a man was arrested swiftly."
Forensics and search experts cordoned off a number of areas in and around Union Street to preserve evidence.