A car bomb exploded at Manila International Airport, injuring at least four people and breaking glass doors and windows, officials said. They said a second bomb exploded about 30 minutes later in the capital's financial district, breaking windows but causing no casualties. Airport manager Aurelio German said investigators believe the airport bombing was an attempt to scare off participants in next week's summit of the Assn. of Southeast Asian Nations, to be held in Manila. In other violence, gunmen killed Pacifico Matias, a candidate for mayor of Lubao, near Manila. He was the sixth candidate killed since campaigning for the Jan. 18 elections began last week.