LONDON, ONT. -- The Special Investigations Unit (SIU) has launched a probe after a man fell from a London balcony Thursday morning.

London police attended a building in the 700-block of King Street about 11:40 a.m.

The SIU says a 21-year-old man made a 911 call about the unwanted presence of a 22-year-old man in his apartment who was refusing to leave.

Police went to the eighth floor and spoke to both men, according to the SIU.

Shortly after, the officers brought the 22-year-old man into the hallway to arrest him for breaching conditions of release.

The 21-year-old remained in his apartment during the arrest and then fell from the balcony to the fourth floor landing of the building, the SIU says.

He was transported to hospital for serious injuries and is in stable condition.

Two investigators and one forensic investigator have been assigned to the case.