The Escape Room

Riddle: Bill, Tracy, Jack, and Jason find themselves trapped in a small room. Each of them was confined in a four-square box with electrified doors in the room and the four of them were all separated by three powerful electric lasers which meant that they could see each other. Fortunately, they had three sheets of paper with them which could help them get out. Bill was in the first box, Tracy was in the second box, Jack was in the third box and Jason was in the fourth box. The four of them were aware of certain events that would occur when they try to escape. They are as follows: 1. One sheet of paper could only be used to deactivate one electric laser. 2. It would take just two seconds (enough time to pass through) before the electric laser came back on. 3. If the electric laser separating Bill from Tracy was deactivated, the electrified door in Bill and Tracy's box would shut down and open but Jason would get fried up in his box. 4. If the electric laser separating Tracy from Jack was deactivated, then the electrified door in Jack's box and Jason's box would shut down and open but Bill would get fried up. 5. If the electric laser separating Jack and Jason was deactivated then the electrified door in Bill's box and Jason's box would shut down and open but Tracy would get fried up. They got out successfully. How did they do it?