Two policemen have been shot dead in a gun battle at Mexico City's international airport.
The shootings were at Terminal 2, near where vehicles drop off passengers.
Witness Israel Lopez, a 23-year-old student said all the people involved appeared to be wearing police-style uniforms.
An airport spokesman said the two dead were police officers, as was another victim taken to a local hospital.
The possible motives in the shooting were still unclear. Nor is it clear if the uniforms the gunmen wore were genuine; criminals in Mexico sometimes wear fake uniforms.
The airport said the terminal and flights were operating normally following what it described as "a dispute in an open-access area."
Shootings at Mexican airports are rare. In 1993 Roman Catholic Cardinal Juan Posadas Ocampo was killed in an airport car park in Guadalajara. Authorities later said his killers had apparently mistaken his car for that of a rival drug lord.