U.S. Customs and Border Protection agents intercepted the vessel around 3 a.m., according to Lauren Mack, a spokeswoman for U.S. Immigration and Customs Enforcement.
Today's discovery was the third of its kind since Saturday morning.
Around 9 a.m. Saturday, the U.S. Coast Guard stopped a northbound 17-foot boat crossing into U.S. waters and found two illegal immigrants and two resident aliens aboard.
On Sunday, a sailboat carrying three suspected illegal immigrants was stopped in San Diego Bay, the Coast Guard reported. It said members of the Coast Guard Maritime Safety and Security Team boarded the 25-foot boat just after midnight and found the illegal border-crossers along with one U.S. citizen.
The detained people were turned over to officers with the Maritime Task Force, which is made up of various military, law enforcement and immigration agencies. Agents with U.S. Customs and Border Protection took the boats.