(CNN) -- Six people died and 13 others were injured Saturday morning in an apartment fire in downtown Las Vegas, authorities say.
Firefighters are investigating but say the fire appears to have been an accident, said Las Vegas Fire spokesman Timothy Szymanski.
Residents told investigators the building didn't have heat and some residents might have been using their stoves for heat, Szymanski said. The fire is believed to have started in the area of the stove in one unit, he said.
Firefighters were called to the Alpine Motel Apartments near North Las Vegas Boulevard around 4:13 a.m., Las Vegas Fire and Rescue said in a Facebook post.
They found heavy smoke and people "hanging out" windows of the three-story structure. Some jumped and were injured, the post said.
"A second alarm was requested along with 10 additional EMS transport units," and the first-floor fire was out in five minutes, the post said.
About 30 people were displaced, Szymanski said.