NEW : four Costner employees -- among four on flight -- were killed , company says . NEW : Their identities have not been released . The flight data and voice recorders were recovered . 63 people remained in the hospital , four in critical condition , mayor says . Plane crashed near Istanbul 's main airport , splitting into 63 parts .
NEW : four Costner employees -- among four on flight -- were killed , company says . NEW : Their identities have not been released . 63 people remained in the hospital , four in critical condition , mayor says . Plane crashed near Istanbul 's main airport , splitting into 63 parts .