Two gun attacks and a knife fight happened within hours of each other in the city on Tuesday, leaving one man dead and three people seriously injured.
In the last of the three incidents a 16-year-old boy was shot in the arm outside Utilita Arena - what was Arena Birmingham and the National Indoor Arena - in the city centre.
He was taken to hospital with serious but not life-threatening injuries after being shot by a gunman in a passing car in St Vincent Street just before 11.40pm.
That shooting happened around six hours after two men were shot at an industrial estate next to City Hospital.
One of the men, aged 31, was killed and a 22-year-old man was seriously injured. He managed to take himself to the eye hospital over the road, where an ambulance was called and he was taken for further treatment.
A 29-year-old man has since been arrested on suspicion of conspiracy to commit murder and remained in custody on Wednesday afternoon.
However no arrests have been made in relation to the city centre drive-by attack.
Both areas were cordoned off in the aftermath of the attacks as specialist forensic officers examined the crime scenes. West Midlands Police said it was too early to know whether the two incidents were linked.
A police cordon was expected to remain in place at St Vincent Street throughout Wednesday, with the tape extending over towards Nelson Primary School opposite the Utilita Arena.
The force is also investigating a stabbing in Burbury Park, Lozells, where a 14-year-old boy was knifed multiple times on a basketball court.
He was also in hospital seriously hurt on Wednesday morning as police examined the area. Nobody has been arrested over the stabbing.
A West Midlands Police spokesman said: "We’re investigating after a teenager was shot in the arm on St. Vincent Street at the back of Utilita Arena Birmingham just before 11.40pm last night.
"A 16-year-old boy was taken to hospital for treatment. His injury is serious but not life-threatening and is not believed to be life-changing at this time.
"The shooting happened near to the bus stop, and the suspects were in a dark coloured vehicle.
"A scene is being held at Vincent Street to allow for officers to conduct searches and a forensic analysis of the area today. A CCTV trawl is already underway.
"There weren’t many people in the area at the time but we believe there were a number of cars passing around the time of the shooting.
"We’re appealing for people who saw what happened and those who have dashcam footage to contact us as soon as possible."
A West Midlands Ambulance Service spokesman said:“We were called at 11:34pm to reports of a shooting in Kelsall Croft, Birmingham. We sent one ambulance, two paramedic officers and the MERIT trauma team with a critical care doctor and critical care paramedic on board, to the scene.
"On arrival, crews found one patient, a teenage boy. He was treated for injuries not believed to be life threatening and was taken to hospital on blue lights and sirens for further treatment.”
Anyone with information is asked to contact police online or on 101, quoting incident number 4747 of April 13, or to call Crimestoppers anonymously on 0800 555111.