CALGARY -- An investigation is underway after two men were shot inside a residential building in the Beltline late Thursday evening. 

Officers responded to Union Square Condominiums in the 200 block of 13 Avenue S.W. just before 10:40 p.m. following reports of gunfire within the building. 

Two men were found with gunshot injuries inside a 15th floor unit but the offender had fled the scene prior to the arrival of police.

As of 8 a.m. Friday, a male suspect was in police custody in connection with the investigation.

EMS confirms to CTV News that a 38-year-old man suffered non-life threatening injuries, while a man in his 50s was in life-threatening condition. Both shooting victims were transported to the Foothills Medical Center where, according to police, their conditions have stabilized. 

Police confirm the offender is known to one of the victim’s friends and the shooting was targeted. 

Investigators are sifting through surveillance footage from the area where the suspect was seen leaving in a vehicle. Descriptions of the suspect and the suspect vehicle have not been released.

Multiple people inside the building have provided statements to officers, but anyone with information about the shooting is encouraged to call the Calgary Police Service non-emergency line at 403-266-1234 or give an anonymous tip through Crime Stoppers at 403-262-8477