LONDON, ONT. -- U.S. Customs and Border Protection (CBP) says its agents at Marysville Station, formerly the Port Huron Patrol Station, arrested four people in an alleged smuggling operation.

It says the four were all illegally in the U.S and that two of the people told agents they crossed the border from Canada in a boat.

Officials say on Monday, agents at Marysville observed a vehicle loitering near the international border in an area where recent smuggling has been attempted.

They say a short time later, local law enforcement conducted a traffic stop on the same vehicle, and requested assistance from border patrol agents. A driver and passenger apparently admitted to being in the United States illegally.

At the same time, another agent observed two people walking along the side of a road parallel to the border with Canada. Officials say the agent suspected that a smuggling event was in progress.

All four subjects were transported to the border patrol station for processing.

CBP says all of the subjects were Brazilian nationals and did not have legal status to be in the U.S.

It says the two individuals who crossed in a boat told agents they had made arrangements to be picked up by the other two subjects after crossing the border.