A Canadian mining firm who one of the tourists had worked for said it was conducting an "intense manhunt" in cooperation with the army.
Philippines army Captain Alberto Caber said the four were taken at gunpoint during a raid late on Monday night on the Oceanview resort on Samal island, near Davao City, the largest city on Mindanao island in the restive southern Philippines.
Military and police officials were surprised by the latest attack, a reminder that insecurity persists in the south despite recent peace initiatives with Islamist rebels.
The Davao region has been relatively peaceful for more than a decade. In 2014, a peace agreement with the largest Muslim rebel group in the south ended 45 years of conflict in which about 120,000 people were killed and 2 million displaced.
"Four people were taken but we do not know what group was behind the attack," Caber told reporters. He said there were about 30 foreign tourists at the resort at the time of the raid.
"It appeared the foreigners were the targets, they were not taken at random," he said.
Caber said the abducted foreigners had been identified as John Ridsdel and Robert Hall from Canada and Kjartan Sekkingstad, the Norwegian manager of the resort. The Filipino woman, identified only as Tess, was Hall's partner.
Nicolas Doire, a spokesman for Canada's foreign ministry in Ottawa, said they were aware of the kidnapping but declined to comment or release information that might compromise rescue efforts or the safety of Canadian citizens.
Shirley Anthony, a spokeswoman for the Calgary-based mining group TVI Pacific Inc, which has a stake in operations in the Philippines, said the company had launched a search for Ridsdel, a semi-retired consultant for TVI.
'Professional kidnappers'
"Right now we are actually in the midst of an intense rescue effort for John, a total manhunt," Anthony said. "The military is involved as well."
She said she did not believe there had yet been any contact with the kidnappers, but that "the people who have abducted him are professional kidnappers for ransom".
The Philippine Foreign Ministry issued a statement of reassurance about the security of leaders, delegates and guests at November's Asia Pacific Economic Cooperation (APEC) summit meetings in Manila.
"The incident in Samal Island is being addressed by our concerned authorities to resolve the issue and ensure that the hosting of the AELM is not affected," said spokesman Charles Jose.
Philippine military sources said the gunmen spoke English and Tagalog, the language spoken widely in the Philippines.
"A Japanese couple was initially seized but they were able to escape with some head injuries," Lieutenant-General Aurelio Baladad, the army's regional commander, told reporters. "
The gunmen and their captives headed to the east in two boats."
Police said a private security guard had recovered a note reading "Justice for our commander, by NPA" posted on the resort's gate five hours after the abduction, the first sign that Maoist guerrillas might be behind the attack.
However, security and local government officials doubted whether the New People's Army rebels had the capability to carry out the attack. "We are still validating that information," said provincial police chief Samuel Gadingan.
Three navy ships were sent to search for the gunmen's boat, while ground units were also alerted to locate possible landing sites in southeastern Mindanao, an army commander said.
In 2001, Islamist militants from Abu Sayyaf, a group linked to al Qaeda, failed to kidnap foreign tourists on Samal island's Pearl Farm resort. Three security men died fighting off the attack.
