Early Saturday morning, at about 4 am, Katonah Fire Department was dispatched for a truck that had reported its brakes had caught fire. Cars 2211 and 2212, along with Engine 115 and Einge 116, responded and, upon arrival, confirmed visible fire at the rear of the truck. Following intial fire suppression, it was determined that fire had spread into the cargo area and was smoldering amongst the large cardboard boxes of used books on board. Tankers were requested mutual aid from Bedford Hills and Goldens Bridge, as our tanker is currently out for routine maintenance. Firefighters used saws to cut holes in the side of the burning trailer to get water into the truck and to let some smoke out. Upon arrival of tow trucks, crews were able to pull boxes out of the trailer and extinguish hot spots. Fire units were on scene for approximately four hours, and two of I-684's three southbound lanes were closed during that time, resulting in a large backup of traffic. Units left the scene at about 8 am. KFD wishes to extend sincere thanks to Bedford Hills FD, Golden's Bridge FD, and Battalion 16 for their assistance at this fire.