Gunmen holding three foreigners and one Filipina hostage slipped past a naval cordon and escaped to remote mountains in the southern Philippines, leaving few clues to their identities, police said Wednesday.

Elite army troops were trying to track the bandits while air force helicopters were readied for a possible rescue as the gunmen trekked into Davao Oriental province, a hotbed of Maoist and Islamic rebels, said Senior Superintendent Aaron Aquino, the region's deputy police commander.

The gunmen seized the Norwegian manager of a luxury island resort on Monday night, along with two Canadian tourists and one of their local girlfriends. The victims were aboard yachts anchored at the resort's marina.

The abductions added to a string of kidnappings of foreigners and locals in the conflict-plagued south since the 1990s, which have been typically carried out by Islamic militants seeking to extort ransoms.

"Rest assured, our security sector will not stop until they catch this group," President Benigno Aquino told reporters.

The president's assurance echoed comments made by the nation's leaders whenever a foreigner has been kidnapped, but the captives' releases have generally only been secured with ransom payments.

Adding to concerns about the captives, police said Wednesday the gunmen had evaded a naval blockade around Samal island, where the abductions took place.

The gunmen had sailed about 50 kilometres (30 miles) east to Davao Oriental, a poor region on the far southeastern edge of Mindanao island close to Indonesia with remote mountains and isolated fishing communities.

"Our scout rangers are following their tracks. They are on their trail. The air force is also helping, ready for insertion," Aquino, the police commander, told DZBB radio.

He said "intelligence" sources had informed police that the gunmen reached Davao Oriental on Tuesday night, but he acknowledged authorities still did not know the gunmen's identities or motives.

"We are waiting for contact from the kidnappers so we will know their demands," he said.

Canadian tourists John Ridsdel, 68, and Robert Hall, 50, were among those abducted, police said.

The other foreigner was the Norwegian resort manager, Kjartan Sekkingstad, 56, and the local woman was Hall's 40-year-old Filipina girlfriend, identified only as Tess.

Chilling footage

Chilling footage from the resort's surveillance cameras emerged on Wednesday showing the gunmen walking their hostages along a jetty at the marina.

In the footage, broadcast by local television networks, a shirtless and bearded male hostage was seen shaking off the grip on his arm of one of the rifle-wielding men, but still not daring to try and run away.

The three others appeared to have been hauled from their beds, with one male hostage shirtless and with a blanket wrapped around his waist. The woman walking next to him was in a night gown.

Investigators said they were looking at the possible involvement of communist guerillas or Islamic rebels excluded from a peace treaty signed in 2014 with the government, according to police.

Communist and Islamic rebels have been waging decades-long struggles that have claimed tens of thousands of lives.

The impoverished southern Mindanao region, including Davao Oriental, has proved fertile recruiting grounds and sanctuary for both groups.

Police commander Aquino said he doubted the involvement of the Abu Sayyaf, an Islamic militant group responsible for the bulk of the kidnappings-for-ransom of foreigners since the early 1990s.

The outriggers used to storm the marina on Samal island were not a "signature" of the Al-Qaeda-linked group, because it typically used high-speed boats, he said.

Nevertheless, armed bandits have in the past kidnapped foreigners and sold them to the Abu Sayyaf, which only has a few hundred armed followers but has withstood a 15-year, US-backed military campaign against it.

In its most recent kidnapping, the Abu Sayyaf boasted getting 250 million pesos ($5.4 million) for the release of a German couple that it held for six months last year on its southern stronghold of Jolo island.

The Abu Sayyaf is currently holding four other foreigners -- a Dutch man, a Korean and two Malaysians, according to the military.