KEARNEYSVILLE, W.Va. (AP) \u2014 A West Virginia Air National Guard member died early Sunday while helping firefighters respond to the the scene of a blaze that had been intentionally set, authorities said.\r\n\r\nThe airman was assigned to the1 67th Airlift Wing in Martinsburg. The unit was part of a mutual aid response to a fire at a vacant structure in Kearneysville, the West Virginia State Fire Marshal's Office said in a statement. The blaze has been connected to nearby fire at another vacant structure reported about 20 minutes earlier, the statement said. Investigators determined that both were the result of arson, officials said.\r\n\r\nBerkeley County Public Safety officials said in a statement that firefighters requested help around 2:30 a.m. and four were taken to a hospital for treatment. It's not clear if the firefighter who died was among the four transported.\r\n\r\nThe West Virginia Air National Guard announced the death with a "heavy heart" and said the service member would be identified 24 hours after relatives was notified.\r\n\r\nThe fire marshal's office said a $5,000 reward is being offered for information that leads to the arrest and conviction of those responsible.