Authorities say they received a report of stabbing on Maple Avenue just after 8 a.m., and responding officers found four wounded individuals, two of whom suffered life-threatening injuries.
According to preliminary information, police believe a man stabbed his girlfriend and her two children before turning the knife on himself.
All four victims have been transported to University Hospital with varying injuries.
The suspect and his girlfriend are both listed in critical condition, while the woman's 23-year-old son and 16-year-old daughter are listed in stable condition.
A third child, an 8 year-old boy, was uninjured during the incident.
The suspect is under police guard and will be charged accordingly.