At least four residents will be displaced after flames broke out in a duplex near Old Colorado City Saturday morning, according to the Colorado Springs Fire Department.

Fire officials said several calls reporting heavy smoke and fire coming from a unit in the 400 block of Olive Street started coming in around 11:15 a.m.  Nearly 30 firefighters and six engines responded to the scene and had the blaze under control within 20 minutes, Lt. Aaron McConnellogue said.

The impacted unit had four residents — none of whom immediately answered phone calls from the department alerting them to the fire. Fire officials said they will continue to try to make contact with the family. No one was inside the residence when the fire broke out.

The unit next door suffered no damage, McConnellogue said. All residents of the neighboring unit were able to safely escape. Officials on scene said they were still determining whether that family will also be displaced.

“Utilities may need to cut power to the entire building, and if they do that, those two additional individuals will end up being displaced with a couple of pets as well,” McConnellogue said.

Fire officials have yet to determine the cause of the fire. Investigations are underway and the department hopes to have more answers within the next few days, McConnellogue said.