Arson has been ruled the cause of a fire last week that destroyed a large portion of a building housing a Warrenton business. Warrenton Fire Chief Mike Owenby said the cause has been determined but an investigation by the Warrenton Police Department is ongoing into who may be to blame. Flames from the fire engulfed the rear Lawn and Landscape Solutions in the early-morning hours on Nov. 30. The business, which opened at the newly constructed facility in July and is owned by James Reid, is located at 602 Progress Parkway on the South Service Road just west of the Preferred Outlets of Warrenton. The renamed business was formerly known as James Reid’s Lawn Service. Owenby said anyone with information on the fire is asked to call 1-800-39-ARSON. A reward up to $5,000 is being offered for information leading to an arrest. “We believe it’s a set fire,” Owenby said. “An unknown individual set this fire.” Following the fire, Owenby described the fire as being suspicious in nature and said there was a “cause for reason” to believe the fire may have been intentionally set. The state fire marshal’s office and the Bureau of Alcohol, Tobacco, Firearms and Explosives were on the scene investigating the damage last Tuesday. A person leaving nearby R.E.P.S. Gym phoned in the fire and firefighters were dispatched at 12:48 a.m., Owenby said. Upon arrival a couple of minutes later, he said flames were already shooting out of the roof and the rear of the building was starting to collapse. Firefighters from four area departments responded to the scene and assisted Warrenton. Crews were on the scene for more than five hours fighting the blaze.