The fire started near the complex, located at 1473 S. 70 East, at about 6:30 p.m., according to Orem Police Lt. Craig Martinez.
Twelve people, including nine adults and three children, were displaced and are being helped by Utah Red Cross.
Martinez said the fire did not appear to be suspicious. Two units are considered a total loss and two other sustained significant smoke and water damage.
Orem Fire dispatch said all Orem units responded to the scene and one unit from Provo also assisted.