At about 4 a.m., a resident of a second-story unit at an apartment building at 25050 Silva Ave., off of Jackson Street, reported smelling smoke coming from an apartment across the hall, Hayward fire Capt. Thor Poulsen said.
Firefighters arrived and broke down the door of the apartment, and found the unit engulfed in flames, he said.
Crews dragged the fire hose upstairs and down a long hallway, and "made a very aggressive attack," extinguishing the blaze quickly, Poulsen said.
They also rescued a small dog, described by Poulsen as a poodle-Yorkie mix. The dog suffered from smoke inhalation but was given oxygen at the scene then taken to a local animal shelter, he said.
The resident was not home at the time of the fire, and no other residents or firefighters were injured.
The apartment where the fire started and its contents were destroyed, he said. Firefighters kicked in the doors to adjacent units while battling the fire, and some other residents were displaced because of that and smoke damage.
The cause of the fire remains under investigation, but Poulsen noted that there was a "very dry Christmas tree" inside the apartment, which he described as "one that was on one of those X-stands, not put in water."
He said cut Christmas trees typically need at least a gallon of water each day to stay hydrated, and warned residents to get rid of any trees that may be dried out.