Up to five people believed to be illegal immigrants of Asian descent remained at large Wednesday afternoon on Guam, a day after a fishing vessel carrying them and others ran aground near the shore of Naval Computer and Telecommunications Area Master Station.

U.S. Navy and police officials said nine immigrants from the boat are in the custody of Immigration and Customs Enforcement.

The nine were found late Tuesday morning on Navy property after they apparently swam to shore, according to Lt. Donnell Evans, U.S. Naval Forces Marianas spokesman.

Naval Base Guam security apprehended them and turned them over to Customs, he said.

Evans said the station, just south of Andersen Air Force Base on the northwest side of the island, is a fairly large but isolated area and houses mostly offices and communications equipment.

Security patrols and checkpoints have increased at the site, but Evans said “it hasn’t been established that they’re actually on base.”

The boat capsized and it hasn’t been determined if everyone on board survived, he said.

Guam Police Department spokesman Allan Guzman said the individuals could be outside the base by now. He asked anyone with information to call the department at 671-472-8911.

Navy and police officials said they still don’t know why the individuals ended up on Guam and what their intentions were.

Anyone entering U.S. soil illegally is a concern and could pose a security threat, Guzman said.

Evans said the vessel was flying a Taiwanese flag, but he did not know the occupants’ nationalities.

Guzman said he knew only that they are of Asian descent.

Officials with ICE could not be reached Wednesday.

The 50-foot boat ran aground on a reef Tuesday morning. The distance from shore was “probably a real quick swim or almost a run in,” said Chief Petty Officer John Brinkman, operations specialist for the U.S. Coast Guard Sector Guam. “It gets real shallow in that area.”

At least one life vest was found on the beach, he said.

A construction worker at the naval site reported the vessel about 7:45 a.m. Tuesday, according to Brinkman.

A water search-and-rescue by the U.S. Coast Guard and the Navy’s Helicopter Sea Combat Squadron 25 has been suspended, according to the Coast Guard.

The boat was still on the reef Wednesday. The Coast Guard is involved in the cleanup of the area, where a petroleum product believed to be from the boat has left a sheen on the water, Brinkman said.