The men, aged 19 and 20, were taken to hospital after the shooting happened in Poplar Road, Bearwood, just before 10pm on Wednesday..
One man has been arrested on suspicion of violent disorder but nobody has been detained on suspicion of firearms offences meaning the gunman could still be at large.
Asked if it was believed to be a targeted attack, West Midlands Police said the investigation was in its early stages and officers were doing all they can to understand what happened.
Poplar Road, which contains shops and flats, was cordoned off in the aftermath of the incident and remained closed on Thursday as specialist officers scoured the area for evidence.
The injured men were said to be in a serious but stable condition, while the 24-year-old suspect remained in custody.
Businesses and shoppers have spoken of their shock at the shooting.
Pervez Khan, aged 49 from Edgbaston, said: "This is not normal around here for Bearwood. A lot of people are shocked."
Mehdi Esmili, 46, who is originally from Iran but now living in Harborne, and who works at Smiley's Cafe, near to the scene of the shooting, said: "People don't feel safe around here."
He said more CCTV is needed to tackle crime.
Dr Ann Jaron, a councillor for Abbey ward, said: "It is very rare indeed, I have never heard of a shooting incident here.
"I have lived in Bearwood since 1986 and I don't remember a shooting incident in that time, it is very rare.
"I am deeply shocked and we would be anxious for police to conclude their enquiries and let us know."
When asked about calls for more CCTV, she said: "If a bit more surveillance would help, then we will certainly ask for it."
Meanwhile police have urged any witnesses to come forward as they try to piece together what happened.
Detective Inspector Jackie Nicholson from West Midlands Police CID, said: “We’re doing all we can to understand the circumstances, find those responsible and take robust action against those who think it’s acceptable to carry weapons on our streets.
“I would urge anyone with information, or if anyone was in the area has dash-cam footage, to please get in touch as soon as possible."
A West Midlands Ambulance Service spokesman added: "We were called to reports of a gunshot incident on Poplar Road at 10pm. Two ambulances, two paramedic officer, a MERIT doctor and a BASICS doctor attended the scene.
"On arrival we discovered two male patients. Both of whom received treatment at the scene before being taken to hospital in a serious condition.
"Both patients had a doctor travel with them to help continue treatment en-route to hospital."
Anyone with information is asked to contact police quoting log number 4570 of March 31.