Chilliwack firefighters were kept busy Thursday with a pair of residential fires, including one that sent four seniors to hospital.

Four elderly residents were taken to Chilliwack General Hospital and treated for smoke inhalation after fire broke out in a three-storey apartment building in the 8900 block of Edward Street just after noon on Thursday.

Assistant fire chief Ian Josephson said the blaze occurred in the kitchen of a ground-floor suite. By the time firefighters arrived, an alarm had alerted the building's occupants, who were already in the process of evacuating.

Thick black smoke clogged the hallway of the ground-floor hallway, but firefighters were quickly able to extinguish the kitchen fire.

"There is extensive fire damage to the kitchen area, with considerable smoke damage to the remainder of the one suite and hallway," Josephson said in a press release.

Fire investigators say the blaze may have been caused by cigarettes discarded in a plastic bucket. They are reminding the public to always extinguish smoking materials in deep, non-combustible ashtrays. Butts should be wet before being placed in the garbage.

Earlier that day, just before 8 a.m., firefighters responded to a fire in the 6000 block of Vedder Road.

They arrived to find smoke coming from a single-wide mobile home.

Crews entered the building and snuffed out a fire in the kitchen area of the trailer.

The home's owner was not home when the fire began. Fire damage was limited to the kitchen, but the rest of the trailer sustained extensive smoke damage.