wildfire
© Reuters/San Bernardino Fire Department
A helicopter makes a drop on a fire which broke out in Arizona and spread into California, sparking the evacuation of two recreational vehicle parks near the Havasu National Wildlife Refuge in California.
A "suspicious" brush fire broke out in Arizona and spread into California on Wednesday, sparking the evacuation of two recreational vehicle parks, as hot and dry weather complicated efforts to contain the blaze.

"It's hot and windy and we're expecting the fire to grow," said Jeff Allen, an engineer and paramedic with the San Bernardino County Fire Department in Southern California. Allen said the fire was 5 percent contained.

The fire broke out as agencies across the western United States gear up for what is expected to be another busy fire season in a region suffering the effects of a prolonged drought, including millions of trees dead from lack of water.

In 2015, more than 10 million acres burned in wildfires nationwide, according to the National Interagency Fire Center.

Authorities said Wednesday's fire started at about 4:30 a.m. local time in the Havasu National Wildlife Refuge, which spans both California and Arizona, and jumped the Colorado River, burning through river bottom vegetation and Salt Cedar and Mesquite trees.

Firefighters from both states are battling the blaze and additional crews have been requested, Mohave Valley (Ariz.) Fire District Chief Ted Martin said in a statement.

Martin called the fire "suspicious in nature," but said it was too early to determine the cause. Officials reported there was no lightning in the area and that skies were clear at the time the fire broke out.

Crews were conducting back-burn operations late Wednesday morning to contain the blaze, Martin said.