Police say that there is no fixed timescale for when the cordon will be removed.
The area surrounding Halifax Place is currently affected by road closures police cordons including Fletcher Gate, Pilcher Gate and High Pavement.
Two boys, aged 15 and 16, sustained stab wounds after the incident that happened around 6.40pm yesterday (Friday 11 January).
Forensic officers have been working throughout the night and detectives are continuing to investigate the circumstances surrounding what happened.
Chief Inspector Donna Lawton said: “It is believed that those responsible for the stabbings are known to the victims and this is unlikely to have been a random attack.
“There will be an increased uniform presence in the area to reassure the public and answer any questions they may have. We continue to work closely with our partners to tackle knife crime, addressing the root cause of this issue, which is seeing effects across the country.
“It is not a simple fix. It needs a multi-agency approach with society taking a stand against knife violence, and we would urge anyone who knows anything about the events of last night to work with us.
“Our officers are looking to establish the events leading up to the incident and to ensure Nottingham City is a safe place to live, visit and work.
“This will include talking to witnesses, conducting door to door enquiries and viewing CCTV and dash camera footage.
“We would like to apologise for the inconvenience caused while the scene is in place, and thank local businesses and the public for their patience. Trams are continuing to run and we will be aiming to minimise any further disruption as soon as we possibly can.”
If you have any information call Nottinghamshire Police 101 quoting incident number 701 of 11 January 2019.