The U.S. Border Patrol in San Diego says three women and a 15-year-old boy were taken into custody after illegally entering the United States from Mexico on personal watercraft.

Agency spokesperson Payam Tanaomi says the four were dropped off near the Imperial Beach pier by the operators of two personal watercraft, who then fled back toward Mexico.

Agents spotted the group late Sunday and arrested the four people on the beach. The women were 18, 20, and 40 years old.

The Border Patrol says personal watercraft are frequently used by immigrant smugglers making a water crossing to San Diego.