MEXICO CITY -- Three policemen died in a shootout with two other officers suspected of drug trafficking at Mexico City's airport on Monday, as panicked travelers scrambled for cover in the busy facility.

The shootout occurred when three federal officers approached the two suspects in the airport's Terminal 2, which handles international and domestic flights. Two agents were killed at the terminal and another later died of his injuries in hospital.

More than a dozen shots were heard, Milenio Television reported. Television footage showed a body lying on the floor of the terminal in what appeared to be a publicly accessible area of the airport.

Three shots rang out at first, witness Israel Lopez, a 23-year-old Mexico City student who had gone to the airport to see off a friend, told The Associated Press. Lopez didn't see who those shots were directed at, but then the gunfire came closer.

Alfredo Estrella / AFP - Getty Images

Federal Police officers stand guard at an entrance near the fast-food area of Benito Juarez international airport Terminal 2, in Mexico City, where two police officers were shot dead and a third was wounded on Monday. Airport spokesman Jorge Andres Gomez said authorities are going through the security cameras to know the exact events of the shooting.

"We were in the food court, and some policemen came in and started shooting at another policeman who was on the floor," Lopez told the AP. "We dove to the floor and covered ourselves with chairs."

Lopez said the shooters wore blue uniforms like those of federal police who provide security at the airport. He said the shooters then ran to the parking area "as if they were pursuing somebody," and he lost sight of them.

'One of the safest places'
Robert Gray, an evangelical missionary from Hart, Michigan, but who has lived with his family in the city of Puebla for the past four years, arrived at the airport after the shooting with his wife, two daughters and son to catch a flight back to the U.S. to visit family.

"It's surprising to see it happening at the airport. It's one of the safest places in the city," Gray told the AP.

The suspects, who remain at large, are believed to be part of a larger group of officials involved in a cocaine ring, Mexico's security ministry said in a statement.

"The Federal Police has identified the two officers who opened fire and several investigative units are now focused on capturing them," the federal Public Safety Department said in a statement.

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Airport spokesman Jorge Gomez told Milenio that aircraft departures and arrivals continued normally after the incident.

The airport said in a press statement that the terminal and flights were operating normally following what it described as "a dispute in an open-access area." But the food court remained blocked to public access for hours after the shooting.

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Mexico City has seen relatively low murder rates compared to the rest of the country, where drug violence has killed around 55,000 people in the past five-and-a-half years.

Severed heads
But attacks have been creeping up in the capital and its surrounding neighborhoods, with more than 300 gangland killings recorded last year.

Mexico's airports and ports are busy areas for drug smugglers. So far this year federal police have seized more than 440 pounds of cocaine at the capital's airport, double the amount taken there last year.

Alfredo Estrella / AFP - Getty Images

A passenger speaks on her cellphone at Benito Juarez international airport Terminal 2, in Mexico City, where two police officers were shot dead and a third was wounded on Monday.

In 2007, the severed heads of three employees of a customs brokerage firm were found near the airport and in the nearby state of Mexico.

The decapitations were apparently retaliation for the seizure of a half-ton of Colombian cocaine at the airport, officials said at the time.

Mexico got wrong man in high-profile drug arrest 

In 2008, federal police chief Edgar Millan was gunned down inside his Mexico City home, and one of the suspects in that killing had worked as an anti-drug officer at the Mexico City airport.

The suspect had a notebook with detailed information on drug trafficking at the airport, and officials said federal investigations into those operations may have been a key motive for Millan's killing.

Reuters and The Associated Press contributed to this report.

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