A man in Washington state has been arrested on suspicion of arson for allegedly starting one of three fires ravaging the Spokane area.

During a press conference on Monday, the Spokane County Sheriff’s Office announced the arrest of a suspect who is accused of starting the Old Trails Fire.

Aaron Farinacci, 37, was arrested by authorities Monday and is being charged with first-degree arson, officials said. Farinacci is being held on a $1 million bond and is expected to appear in court Tuesday.

The Old Trails Fire was initially reported on Aug. 1 at approximately 12:00 p.m., near the intersection of N. Old Trails Road and W. Euclid Road.

Sheriff John Nowels of the Spokane County Sheriff’s Office said a witness reported seeing a man in the area “looking very nervous.”

Once the witness returned home, he saw smoke coming from what was believed to be the area where he says he saw the man. The witness then called police to report his observations.

That man, later identified by officials as being Farinacci, was found about a mile and a half from where the fire was burning, according to authorities. He was detained, questioned and later released by authorities that same day. Farinacci was in possession of waterproof matches and a butane lighter at the time, officials said.

The sheriff’s office said an investigation is ongoing, as is the investigation into the Autumn Lane and Fairview Fires.

All three fires ignited on Saturday afternoon, authorities said. Together, the three fires are being called the Spokane Complex Fire.

As of Monday afternoon, the three fires had together burned more than 10,000 acres with 0% containment, according to officials. At least 700 structures, including homes and businesses, have been destroyed in the ongoing fires.

“It’s unprecedented in this community. Frankly, it’s unprecedented in many areas of this country,” Tom Clemo, the fire incident commander, said at a news conference on Monday with Washington Gov. Bob Ferguson.