The air carrier flight had been experiencing light, occasionally moderate, turbulence throughout the flight. The captain had asked the flight attendants to secure the cabin earlier than usual, while they were in light turbulence, because the conditions were not expected to improve before arrival at the destination airport. The airplane was at flight level 240, when the flight attendants began the final preparation for landing. During that time, with no echoes depicted on the weather radar, the airplane experienced unexpected severe turbulence for 1 to 2 seconds. The maximum g recorded was 1.773 and the minimum g recorded was 0.391. All three flight attendants were standing at the time, preparing the cabin, when they were jolted upward and then fell to the floor. Two of the flight attendants sustained minor injuries, while one flight attendant was seriously injured. The airplane was not damaged and landed uneventfully at the destination airport.