The airport spokesman said the victims are federal police officers.
The federal Public Safety Department says at least one was an officer, but was checking the identity of the others.
Details of the shooting are still unclear.
Airport spokesman Jorge Gomez told local media that the airport was operating normal following early Monday’s shooting, which occurred in a passenger drop-off area at the entrance to the second of two terminals at the airport.
Shootings at Mexican airports are rare. In 1993 Roman Catholic Cardinal Juan Posadas Ocampo was killed in an airport parking lot in central Mexico.