Gunmen opened fire outside Manila international airport Friday, officials said, killing four people including the mayor of a town in the southern Philippines, where political violence is endemic.

Terrified men and women screamed and cried while a man, apparently fatally wounded, lay face down on the pavement outside the passenger terminal in a video clip uploaded to the local GMA television network's website.

"The mayor and his family and some security escorts were attacked," Manila airport general manager Angel Honrado told reporters, adding one of the dead was the mayor of Labangan town in the troubled southern region of Mindanao.

Ukol Talumpa, a member of the political opposition, won a hotly contested election for mayor of Labangan in last May's elections, defeating the incumbent who is a political ally of President Benigno Aquino.

The official, his wife, other members of his family and their bodyguards were shot at by at least two men as they stepped out of the passenger terminal shortly after getting off a flight from the southern Philippines, Honrado said.

Four people were killed and four others wounded in the broad daylight shooting, he said, adding "the mayor and his wife" were among the dead.

He said he could not confirm television news reports quoting unnamed eyewitnesses as saying the two suspects were wearing police uniforms.

Airport security forces chased after the gunmen but they escaped on a motorcycle in the heavy late-morning traffic outside the terminal, he added.

Honrado, speaking alongside Manila police officials at a news conference, said the authorities did not know the identity of the gunmen nor the motive for the attack.

The Philippines is infamous for a brutal brand of democracy where politicians -- particularly at local and provincial levels -- are willing to bribe, intimidate or kill to ensure they win.

More than 60 people were killed in last May's elections, when 18,000 posts from provincial governor to town and city mayors as well as city and town executive councils were contested.

In the footage obtained by GMA, which it said was taken by a bystander, spilled luggage and trolleys lay scattered on the curb on both sides of the gunned down man.

Two other people were shown crouching on the curb, while the voices of screaming men and women could be heard.

A taxi cab and four vans, all their doors open, were stopped on the driveway, with the hazard lights of one van still blinking on and off.

Police are withholding the identities of the other victims pending notification of next of kin, Honrado said.

"This is a very unfortunate incident that did happen at Terminal 3," Honrado said.

"Government agencies are trying their best to determine the perpetrators and bring them to justice."

He appealed to other passengers who witnessed the shooting to help the police identify the suspects.

Talumpa was the former vice mayor of Labangan who successfully challenged Aquino ally and incumbent Wilson Nandang for the mayoral post in the last election, according Leo Santillan, spokesman for the provincial government of Zamboanga del Sur, which includes Labangan.

Santillan told reporters in Pagadian city, the provincial capital, that Talumpa, a member of the Nationalist People's Coalition Party, had flown to Manila earlier in the day with his wife, two nephews and six other people.