Evacuations in place as Northern California county battles 2 blazes

Two wildfires exploded overnight in northern California, forcing evacuations in a rural community amid the continued fire threat.

The Mill and Mountain fires are "two fires of significance" in Siskiyou County, Cal Fire Chief Deputy Director Chris Anthony told reporters during a briefing Saturday.

Gov. Gavin Newsom declared a state of emergency in Siskiyou County to support the response to the "rapidly-spreading" Mill Fire, which ignited Friday afternoon and quickly spread north due to strong winds.

There have been some civilians injured in the fire, Cal Fire spokesperson Suzi Brady told ABC News. She said they were transported to the nearest hospital though she did not know the extent of their injuries.

There have also been structures destroyed in the blaze, she said, but noted the damage inspection team is still assessing the extent of the damage.

Anthony said an estimated 50 structures have been damaged or destroyed in the fire, though "we do expect that number to rise" based on in-the-field observations.

The fire has burned nearly 4,000 acres and is 20% contained as of Saturday morning after "large numbers of resource arrived throughout the night," according to fire officials. Evacuation orders are currently in place.

The blaze started in the city of Weed, which saw significant damage from the Bulls Fire in 2014. Weed Mayor Kim Greene told ABC News the community is devastated by the latest fire to impact the area. Though official assessments are still pending on structures damaged, Greene said she believes "the count is over 100 homes lost."

The county is also battling the Mountain Fire, which was "extremely active" overnight, burning nearly 3,400 acres in mostly rugged terrain since starting Friday evening, fire officials said Saturday morning. The fire is 5% contained.

Evacuations have also been ordered due to the Mountain Fire, which is currently burning outside of residential areas, Brady said.

The cause of both fires is under investigation.

The incidents are "rapidly changing and our staff and partners are doing everything they can to get everyone to safety," the Siskiyou County Sheriff's Office said on social media Saturday.

A red flag warning has been issued for the area due to strong wind gusts combined with low relative humidity.

Anthony urged people to take caution this Labor Day weekend amid extreme heat and persistent drought -- the "perfect ingredients for rapid fire spread."

"It's important to understand that 95% of all fires start as a result of human-caused activity," he said. "It only takes a spark to ignite a major fire."

ABC News' Kenton Gewecke and Alyssa Pone contributed to this report.