Gunmen kidnapped three foreigners, including two Canadian tourists and a Norwegian resort manager, as well as a Filipino woman, from a popular resort in Philippines late on Monday.
The four were kidnapped from the Samal island in southern Philippines, and were taken to the Mindanao mainland on a boat by the gunmen, the Philippines army said, according to Reuters.
"Four people were taken but we do not know what group was behind the attack. It appeared the foreigners were the targets, they were not taken at random," Philippines army Captain Alberto Caber told the media on Tuesday.
Navy ships were sent in to look for the boat, while the army sent in ground troops to inspect areas near the Mindanao mainland.
Islamist militants have often carried out attacks in Philippines' restive southern region, though a peace agreement reached last year with a Muslim militant group had seen some calm in the area.