San Francisco has been left under an eerie orange glow as a result of the smoke from the fires blazing across the western United States.

Wildfires raged unchecked across large parts of the western United States on Wednesday in blazes unprecedented in their scale and ferocity, as Oregon warned of many deaths after blazes destroyed at least five small towns.

Winds gusting as high as 80km/h (50mph) fanned dozens of catastrophic fires across a large swathe of Oregon and neighbouring Washington state – places that rarely experience such intense fire activity because of the Pacific Northwest’s cool and wet climate.

Flames ravaged the towns of Detroit, Blue River, Vida, Phoenix and Talent, Oregon Governor Kate Brown said Wednesday.

The blazes, which also forced the evacuation of much of Medford in southern Oregon, could bring “the greatest loss in human lives and property due to wildfire in our state’s history”, Brown said at a news briefing.

In Washington state, a one year old boy was killed and his parents badly burned as tried to flee a fire, police said.

Nearly 100 fires are raging across the west of the US, with 28 in California, where nearly 930,800 hectares (2.3 million acres) have been burned and three people were on Wednesday confirmed dead. A massive cloud of smoke has enveloped much of the state leaving San Francisco beneath an eerie orange glow.

A 12-year-old boy and his grandmother died in a wildfire about 50 miles south of Portland, KOIN News reported. In Washington state a 1-year-old boy was killed and his parents severely burned as they tried to flee a fire in Okanogan County, police said.

Firefighters retreated from uncontrollable blazes in Oregon as officials gave residents “go now” orders to evacuate, meaning they had only minutes to leave their homes.

“It was like driving through hell,” Jody Evans told local television station NewsChannel21 after a midnight evacuation from Detroit, southwest of Portland.

Officials in the Pacific Northwest said they did not recall ever having to deal with so many destructive fires at once in the areas where they were burning.

In suburban Clackamas County, home to about 420,000 people who mostly work in nearby Oregon, four major fires were burning, with sheriff’s deputies travelling with chainsaws in patrol cars to remove fallen trees blocking roads.

“These winds are so incredible and are spreading so fast, we don’t have a lot of time,” said Clackamas County Sheriff Craig Roberts.

Fires were burning in seven Oregon counties, and rural and suburban homes miles away from Portland, Oregon’s largest city, were under preliminary orders to prepare for possible evacuations. Three prisons were evacuated late on Tuesday.

Brown saw no respite to the hot, windy weather and requested a federal emergency declaration for the state.

“Absolutely no area in the state is free from fire,” said Doug Graf, chief of fire protection for the Oregon Department of Forestry.

The Pacific Northwest is no stranger to wildfires, but most of the biggest ones until now have been in the eastern or southern parts of the region – where the weather is considerably hotter and drier and the vegetation more fire-prone than it is on the western side of the region.