(CNN) Six people died and 13 others were injured Saturday morning in an apartment fire in downtown Las Vegas, authorities say.

In a news release , the Las Vegas Fire and Rescue said firefighters arrived at the Alpine Motel Apartments not long after 4 a.m. and found people jumping out of windows. Black smoke poured out of the wood frame, 42-unit building near Las Vegas Boulevard North.

Firefighters went inside and discovered the fire in an apartment, the fire department said. The fire department said it appears the fire started around a stove in that apartment and was accidental.

Residents told investigators the building didn't have heat and some residents might have been using their stoves for heat, Las Vegas Fire spokesman Timothy Szymanski said.

Firefighters found three people dead inside the building, one dead on the sidewalk and two dead at an unspecified location, the news release said. Their identifies have not been released.

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