More than 138 new wildfires broke out on Saturday alone, raising the total to about 240, according to local media reports.
More than 1,800 firefighters were tackling the fires and a further 260 were coming to their aid from other parts of Canada. Saskatchewan was sending three air tankers and 30 firefighters.
"Given the current wildfire situation and the expected increase in wildfire activity, the province is taking this extraordinary measure of declaring a provincial state of emergency," Todd Stone, British Columbia's transportation and emergency management chief, said in a statement.
John Ranta, the mayor of Cache Creek, one of the areas where local residents were ordered to evacuate, said at least five properties had been destroyed by fire as well as 30 trailer park homes and two hangars at an airport.
One firefighter said: "I've been in this business for 17 years... and I haven't experienced a day like we experienced yesterday."
Weather conditions are further fuelling the conflagration. The Weather Network said that a ridge of high pressure was keeping up temperatures, pushing hot, dry desert air through the Prairies. Lighting storms also lit up the skies in many parts of the province.
“Yesterday was an extraordinary day in terms of fire activity across the province,” Kevin Skrepnek, chief information officer for the BC Wildfire Service, told the National Post.
“We’re focusing now on public safety, keeping these fires away from communities, protecting transportation routes, things like that.”
He added that around 120 firefighters were deployed to build fire guards to impede the progress of the blazes.
The last time British Columbia declared a state of emergency was in 2003.
Factors which triggered the emergency include weather conditions and man-made causes. In an interview with the Globe and Mail, Mr Skrepnek said: “A big driver of activity yesterday was the lightning we were getting, but there were definitely human-caused fires in there as well – which is frustrating, given that those are preventable fires.”