What happened
While cruising at 4,000 feet, the flight crew received a traffic report from Air Traffic Control. Due to instrument meteorological conditions, the crew was unable to visually identify the reported traffic.
Approximately three minutes after the initial report, the aircraft's Traffic Collision Avoidance System (TCAS) issued an alert instructing the crew to climb. In response to the alert, the pilot initiated a climb from 4,000 feet, eventually leveling off at 5,300 feet.
During this period of ascent, two flight attendants were standing in the cabin performing pre-landing duties. The motion of the climb caused both attendants to fall. One flight attendant sustained a broken leg, while the other was not injured.
The pilot notified Air Traffic Control that an ambulance would be required at the destination airport. The aircraft landed without further incident, and the injured crew member was transported to a local hospital.