A bomb explosion at Zamboanga airport in the southern Philippines has killed two people and injured 24.
The blast on Thursday killed the suspected bomber immediately and caused the death of a bystander on Friday.
It came just before the US ambassador to the Philippines, Harry Thomas, was to arrive; he cancelled the visit.
The US maintains a rotating force of at least 500 troops in the south of the country where overlapping insurgencies and kidnap gangs are operating.
A British resident of the area, 69-year old Charles McKercher, was among the injured.
The police chief, Senior Superintendent Edwin de Ocampo, said witnesses and security cameras suggested the bomb had been carried by the attacker into the airport hidden in his backpack.
"He was the one who carried the bomb pack. We are investigating if he is a suicide bomber," Mr de Ocampo said.
There is no history of suicide bombing in the area.
Police are investigating the theory that the suspected bomber may not have known he was carrying a bomb which may have been detonated remotely.
The Governor of Sulu, Sakur Tan, has said he thinks the bomb was intended for him.
Governor Tan has led aggressive campaigns against the Abu Sayyaf, a kidnap gang based in his area.
He was grazed by the explosion when he arrived off a plane from Manila.
"I believe I was the target," Mr Tan told reporters, saying the device went off just a metre away from him.
"I saw the flash very clearly."
"I have received intelligence reports that I would be bombed," he told local TV on Friday.