Authorities on Monday were searching for suspected undocumented immigrants who were believed to have been aboard a Mexican fishing boat discovered off the Palos Verdes Peninsula.
Some 25 people -- 19 men and six women -- were detained after the U.S. Coast Guard discovered the 40-foot, open-hulled boat with an outboard motor, known as a panga, in an area off Palos Verdes known as Abalone Cove.
Two vans were waiting on a nearby road to pick up the suspected undocumented immigrants, authorities said.
Port police, Los Angeles County Sheriff's deputies and others assisted in the search for possibly 15 other people believed to be aboard.
Traffic along one of the main roads around the peninsula was backed up as authorities conducted their investigation. No contraband was found on the boat, said special agent Joseph Macias of Homeland Security Investigations.
Residents woke to find federal and local police chasing people through bushes and along hillsides of the exclusive coastal community of Portuguese Bend.
"They swarmed the hill," said resident Tom Redfield. "They caught the majority of them right here and then we kept finding them all over the place. There's so many places to hide."
The discovery comes about one week after the first law enforcement death during a confrontation with a Mexican smuggling boat in the waters of Southern California.
Federal authorities have seen an increase in the number of boats smuggling drugs and people further north along the California coast to get around stepped up security at the U.S.-Mexican border in recent years.
In the first two months of this fiscal year -- October and November -- there were 44 maritime-smuggling incidents detected in Southern California, including seven in the Orange, Los Angeles and Ventura counties, compared with 35 in the same period last year, said Virginia Kice, a spokeswoman for Immigration and Customs Enforcement.
The problem became so big that Santa Barbara County Sheriff Bill Brown wrote a letter to his local congresswoman in April, saying that a recent discovery of a "Super Panga" off the coast was nearly too much for his understaffed department to handle.
He said recent probes have uncovered meth and undocumented immigrants coming on pangas from China.
"We have great concern that other items could be smuggled ... including deadly weapons and terrorists," Brown wrote to Congresswoman Lois Capps, D-Santa Barbara.