Smoking is the likely cause of Wednesday morning's fire that caused significant damage to the Skyline Apartments in Riverdale, says Whitehorse fire chief Clive Sparks.

'It's the only thing we can come up,' Sparks said in an interview this morning.

The fire chief is now estimating the fire caused about $250,000 in damage and $40,000 in contents destroyed or ruined by smoke damage.

The fire damage was contained to the first-floor apartment where it started in the bedroom, though neighbouring apartments were consumed by smoke.

None of the residents had to be rescued or assisted from the apartment building after firefighters arrived, though six, including the occupant of the apartment where the fire started, were taken to Whitehorse General Hospital to be examined for smoke inhalation.

Part of Lewes Boulevard was closed to traffic as firefighters extinguished the blaze, which broke out shortly before 9 a.m.