INDEPENDENCE, Mo. -- The Independence Fire Department confirmed Wednesday night that an apartment fire that killed a family of four started because of a stovetop left unattended. The tenant tried to “start something on the stove top, the smoke detector activated, and they went back in, attempted to use the extinguisher, and then left the left the apartment.” The fire quickly spread to other parts of the complex, including to the family’s unit, where they were trapped inside according to the fire department. “Our crews upon arrival had heavy fire on the second and third floor and through the roof,” Fire Chief Jimmy Walker said. Person seriously injured after being struck by KCMO Parks and Rec pickup truck It wasn’t long before they noticed the building was beginning to crumble. “That's the only reason we pulled out is because we actually had guys inside and gals inside when the building started to collapse,” Walker said. Tim Gardner lives in the complex; he woke up the fire already burning. “I seen flames there. I mean, I don't know what to say. It's in flames. It was horrible for sure,” he told FOX4 on Wednesday. He said the complex is quiet, everyone typically keeps to themselves, but that people were friendly and that it’s a good place to live. Having four people lose their lives is weighing on him. “Oh, my God, yes. That was horrible, very horrible,” tenant Tim Gardner said. “That is very emotional, and I feel bad for their families and everything. So, yeah, it was just a horrible thing this morning, man and I pray for everybody involved.” While Independence police work to contact the family of the deceased, Walker said there are lessons for everyone to learn about fire safety. “We need to make sure that we never leave cooking unattended, okay? That's how quickly things can escalate. As you can see in this instance, that when we leave cooking unattended, catastrophe can happen," he said. He mentioned that if a fire starts in an apartment, closing the door can help contain the fire until crews arrive. “It's unfortunate. We have to talk to the family of someone who's deceased in a structure fire and let them know that this happens. I don't wish it on anybody,” Walker said. “I don't wish it on my crews who had to go in and find them. And I was with them. And I don't wish that on anybody. It's a horrific scene.” Download the FOX4 News app on iPhone and Android Gardner said he’s feeling the same way. “It takes a toll on you, like just knowing that this happened in my building and my complex hurts a little. I'm sorry for the families involved; this was a horrible situation for sure.”