MILWAUKEE (CBS 58) -- Milwaukee Fire Department responded to a fire at the four-story Edenbrook Lakeside nursing facility near Prospect and Woodstock early Thursday.

Officials confirm to CBS 58 that the fire was confined to a single unit. Despite the fire being contained, the activation of the sprinkler system led to significant smoke production. The fire alarms and sprinkler systems were reportedly operational during the incident.

The response began after calls were received at around 3:11 a.m., leaving four individuals being transported to the hospital. Among them, three suffered from smoke inhalation, while one sustained burn injuries, the severity of which was not immediately known by MFD.

Investigations into the cause of the fire are ongoing.