At 22:32 CDT, a Boeing 757-2G7 operated by America West Airlines encountered turbulence while cruising at FL310 near Abilene. The airplane was undamaged, but three flight attendants in the aft galley sustained injuries (one serious and two minor), and one flight attendant was not injured. No one else on board was injured. The aircraft was en route from Orlando, Fla., to Las Vegas, Nev., when the captain noted a line of thunderstorms. The captain advised the flight attendants to suspend service and stow the carts, and five or six minutes later the aircraft was hit with two strong jolts of turbulence. It was a dark night and the airplane was flying in and out of clouds. There was no visible lightning in the immediate area and no precipitation was observed.