Nottinghamshire Police say they were called at 4:50 pm on Sunday 22 January.
The incident happened at Phoenix Close in The Meadows where a man was reportedly injured in an attack at a property.
DI Jon Kerry, of Nottinghamshire Police, said: “Lines of inquiry are ongoing, which include checking CCTV footage, and we are working hard to establish the full circumstances surrounding this incident.
“We’re urging anyone who recalls seeing suspicious activity in the area around this time to contact us immediately as they may have valuable information which could help us with our investigation.”
“Anyone who has any information is urged to call Nottinghamshire Police on 101, quoting incident number 126 of January 22, or call Crimestoppers anonymously on 0800 555 111.”