Shortly after midnight on Saturday 11 May, officers were called to Montgomery Square, Wath, following reports of an assault.
A 17-year-old boy was taken to hospital with serious injuries, where he remains in a critical condition.
A 19-year-old man from Wath was arrested shortly afterwards and remains in police custody.
Cordons will remain in place today as officers carry out enquiries.
If you witnessed the incident or have any information which could assist officers, we would like to hear from you. Please call 101 quoting incident number 6 of 11 May 2019.