Mexico - Three Mexican policemen have been killed in a shootout with two other officers at Mexico City's main airport.

   Officials say those shot dead were attempting to arrest the two officers who are suspected of involvement in a cocaine trafficking ring.

   Passengers dived for cover when the suspected traffickers opened fire, killing two officers immediately and injuring a third who later died.

   The two suspects escaped and are being sought by the authorities.

  Officials said they had spent 18 months investigating corrupt federal and local officials who they suspect are part of a drug trafficking ring operating at the airport.