On November 9, 2002, about 1350 eastern standard time, a McDonnell Douglas MD-82, N452AA, operated by American Airlines as flight 710, performed an emergency evacuation after landing at LaGuardia Airport, Flushing, New York. Two certificated airline transport flight crew members, 2 flight attendants, and 68 passengers were not injured. One passenger sustained a serious injury, while one flight attendant and five passengers sustained minor injuries. The airplane was not damaged. Visual meteorological conditions prevailed and an instrument flight rules flight plan had been filed for the scheduled passenger flight conducted under 14 CFR Part 121. According to a representative of American Airlines, the airplane landed uneventfully and taxied toward the parking area. While waiting on the ramp, the flight crew started the airplane's auxiliary power unit (APU) and about 30 seconds later, the cabin began to fill with smoke. The captain ordered an emergency evacuation utilizing the airplane's four evacuation slides. All slides functioned normally; however, during the egress a passenger sustained a fractured bone in her right foot. According to a Federal Aviation Administration inspector, examination of the airplane by maintenance personnel revealed a broken hydraulic line, which allowed hydraulic fluid to accumulate in the area of the APU inlet.