  Specific heat, resistivity, susceptibility and Hall coefficient measurements
were performed on high-quality single crystalline Na$_{1-\delta}$FeAs. This
compound is found to undergo three successive phase transitions at around 52,
41, and 23 K, which correspond to structural, magnetic and superconducting
transitions, respectively. The Hall effect result indicates the development of
energy gap at low temperature due to the occurrence of spin-density-wave
instability. Our results provide direct experimental evidence of the magnetic
ordering in the nearly stoichiometric NaFeAs.
