Six people, including a 13-year-old boy, have been arrested on suspicion of murder after a 14-year-old was chased and stabbed to death in Birmingham.
Police said a post-mortem examination confirmed the male victim died from a stab wound to the chest.
A 33-year-old man was arrested from an address in Kingstanding, Birmingham, on Tuesday afternoon.
A 13-year-old boy was later detained in the Walsall area.
Police said another man aged 38 and a 14-year-old boy were arrested from a vehicle in Cheshire while two men, aged 36 and 35, surrendered to separate police stations in the West Midlands.
All six suspects remain in custody, police said.
The young victim is thought to have been chased into College Road in the Kingstanding area of Birmingham at around 7.30pm on Monday before being stabbed.
An ambulance arrived at 7.35pm but the boy was confirmed dead at the scene a short time later.
The arrests come after West Midlands Police said there is “nothing to suggest” the stabbing was racially-motivated.
Officers later added they are “keeping an open mind” about the motive for the attack.
The force has voluntarily referred the case to the Independent Office for Police Conduct (IOPC) after “looking at previous incidents involving the victim”.
Two groups of youths clashed in front of police near to the scene around an hour after the stabbing.
Sky correspondent Frazer Maude said police quickly dealt with the incident and the two groups were separated.
Some were placed in handcuffs but police have said no arrests were made.
Detective Chief Inspector Stu Mobberley, who is leading the investigation, said: “We’ve made rapid progress on the investigation so far and these arrests are a significant step forward.
“Our officers have executed a series of warrants in the region and we’ve worked with police forces outside the area to apprehend suspects.
“We’re still speaking to witnesses and really need to hear from anyone who has seen or heard something, even if they think we may already know or they’re not sure how important it is.
“We are aware of many different rumours circulating about the motive for the murder but we are keeping an open mind and pursuing all lines of enquiry. We ask people not to speculate on social media.”
Labour MP Jack Dromey, whose Erdington constituency includes the area where the stabbing happened, said: “Truly shocking that a 14-year-old teenage boy in Kingstanding was stabbed to death this evening.”
Anyone who can help the investigation is asked to contact police by Live Chat on the force’s website, calling 101 quoting log 3313 of 31/5, or calling Crimestoppers anonymously on 0800 555 111