SUGAR CREEK, Mo. -- As of Monday, the cause of a fire damaging a home in Sugar Creek that left six people injured, including four firefighters, is still under investigation. The state Fire Marshall’s Office is joining in on the investigation, along with fire investigators from the Sugar Creek Fire Department, and the IPD/IFD Joint Fire Investigative Team. The Sunday house fire was described as a "rapidly changing." "Sometimes it happens without warning, you don't know it’s coming. You go into a room that has very little, very light smoke, you get across that room turn around and look and then half the room could be on fire,” Eric Michel, battalion chief of Fire Prevention with the Independence Fire Department shared Monday. Florida boy undergoes open heart surgery after being hit by drone Sugar Creek Fire requested assistance from neighboring City of Independence. "Our dispatch advised there was an occupant was trapped in a bedroom, or two occupants in the house, at the time of dispatch. Our guys immediately called for mutual aid from Independence Fire. When we arrived on scene, our police officers were able to get one of the occupants out of the home. There was a male occupant in the back bedroom who was still trapped in the house,” Sugar Creek’s Fire Chief Nate Richardson said. Responders quickly went in, made contact with a disabled man in a back bedroom of the home, then established a plan to evacuate him and get him help from critical injuries. FOX4 was told the home was a smaller one and trapped a lot of the heat from the Sunday morning fire in. “Found out it was bad enough and it could have been way worse. Your heart sinks,” Michel shared when he received the news of some of his crew hurt. Four Independence firefighters were hurt; two were taken by an ambulance to get medical care. "One of those had significant burns on his back, as well as a dislocated shoulder. The other had significant burns on his back as well,” Michel shared. “We are just really glad all of our guys get to spend Christmas with their family.” Of those two injured, they arrived at a local hospital then went on to an area burn unit. All four firefighters have been released from the hospital, FOX4 learned Monday. The two residents of the home were also hurt. As of Sunday, one was treated and released Sunday. The other is critical condition and is still receiving care. According to the Independence Fire Department, at about 7:30 a.m., crews were dispatched to the area of South Forest Street and Henry Avenue on reports of a house fire with people trapped inside. Units with the Sugar Creek Fire Department responded to the scene and later requested backup from IFD. Download the FOX4 News app on iPhone and Android Upon arrival, Independence crews were told that one person had made it out of the house and another was still trapped inside one of the bedrooms. Independence fire crews began their recovery efforts and in the process, four IFD firefighters were injured. According to IFD, one firefighter was treated on the scene and released, and three others were taken to a hospital for burn injuries.