Police investigating the deaths of two Big Issue sellers in Birmingham said victims Wayne Lee Busst, 32, and Ian Watson Gladwish, 31, may have known their attacker.
– Detective Inspector Buck Rogers, West Midlands Police
We have had a fantastic response from the public so far and their information has proved vital to our investigation.
Early enquiries suggest that this wasn't random. The attacker appears to have known his victims.
Detective Inspector Rogers appealed for anyone who witnessed the stabbings on Friday evening to contact police on 101.
Police have identified the two men who were stabbed to death in Birmingham on Friday.
Wayne Lee Busst, 32, and Ian Watson Gladwish, 31, were both Big Issue sellers based in the city centre. They were stabbed just before 6pm.
A 23-year-old man arrested on Friday evening remains in custody. A warrant of further detention was issued this morning, allowing officers to question the man until 21.00 tonight.
Police are continuing to question a man over the fatal stabbings of two Big Issue vendors in a busy city centre.
West Midlands Police believe hundreds of people may have witnessed the attacks that took place in Birmingham's Union Street just before 6pm on Friday.
A 23-year-old man was arrested shortly afterwards near the Odeon Cinema in New Street and remains in police custody.
The founder of The Big Issue magazine, John Bird, condemned the double killing as "utterly senseless".
A police spokesman said the victims have been identified but their details are not yet being released.
The Big Issue has confirmed both stabbing victims were sellers of the publication.
In a statement, founder and Editor-in-Chief John Bird says he and his staff are deeply saddened.
"Myself and everyone at The Big Issue has been deeply saddened to hear the tragic news that two of our well-liked Birmingham based vendors were stabbed to death in the city centre yesterday evening.
"We are struggling to make any sense of this utterly senseless attack, and our sincerest condolences go out to the families of the victims.
– John Bird, The Big Issue founder and Editor-in-Chief
"This awful crime, perpetrated against two hard working, mild mannered men, only serves to illustrate the extreme vulnerability of people who live and work on the streets. Which is why we at the Big Issue are constantly striving to create opportunities which will help our vendors to get off the streets and out of harms way.
"We are truly devastated that these two individuals have been deprived of just such a future."
Union Street in Birmingham City Centre has now re-opened following the incident last night. investigations are ongoing
Police renew appeal for witnesses following double stabbing in Birmingham city centre last night http://t.co/Zu56eAHP
Superintendent Richard Moore of Birmingham Central Police said the fatal stabbing of two men in Birmingham city centre was a "dreadful" and "exceptionally rare" incident.
A man has been arrested after two men, believed to be in their 40s, were stabbed in Birmingham city centre, just before 6pm this evening.
West Midlands Police said one victim is understood to have been stabbed outside a Sainsbury's store in Martineau Place whilst the second man was found slumped near Boots in Union Street. Both were pronounced dead at the scene.
A man was arrested in New Street near the Odeon Cinema shortly after the stabbings.
Passers-by gave first aid to the two victims of a double stabbing that happened in Birmingham city centre this evening.
The Ambulance Service say a number of emergency calls were received from members of the public shortly before 6.00pm this evening.
Medics including two doctors and three ambulance crews arrived at the scene to find "excellent first aid being given by police and passers-by".
Both men suffered cardiac arrests despite "advanced life support" given to both victims by medics. The men believed to be in their 40s were pronounced dead at the scene.
One man was arrested minutes after the stabbings, of which police say there were "potentially hundreds of witnesses".