Dallas Fire-Rescue crews worked Thursday morning to put out an apartment fire in Northwest Dallas near the Medical District. According to officials, the fire started around 6:30 a.m. at 4619 Lake Avenue in Dallas near Maple Avenue. NBC 5 crews observed multiple firefighters battling the blaze, several of whom were on the roof of the apartment that appeared to have sustained smoke damage. The investigation into the cause of the fire is ongoing. It is not clear if anyone was injured during the blaze. Check back and refresh this page for the latest update. As developments unfold, elements of this story may change.