LOS ANGELES - Three people were killed and 27 others injuried after a suspected smuggling vessel overturned Sunday off the coast of the US city of San Diego, authorities said.

The accident took place at about 10 am local time (1700 GMT) off the coast of the Point Loma peninsula near the Cabrillo Monument, which is San Diego's only National Park, according to the San Diego Fire-Rescue Department.

Lifeguards received the initial notification of the vessel in question experiencing trouble via VHF radio from a tow vessel that was in the area. The reporting party indicated that one person was on board, said the department in a release.

Multiple agencies responded to the scene immediately. Officials said that lifeguards responding to the area found a cabin cruiser, which had broken apart against the rocks off the coast, and 30 people were in the water.

Jeffery Stephenson of the San Diego sector of US Customs and Border Patrol told reporters that officials had "every indication" from their perspective that "this is a smuggling vessel used to smuggle migrants into the United States illegally."

"We haven't confirmed the nationality of people involved. But our agents are with many of them at the hospital and the man who we believe was the operator," he added.

"The ocean is inherently unsafe. The reality is crossing the border illegally is unsafe no matter the method," Stephenson noted, slamming smugglers who treat people as commodities.

"They don't care about the people they're exploiting. All they care about is profit to them," he said.

Park officials of the Cabrillo Monument said on Twitter after the incident that the tidepools of the park "are temporarily closed" and they "will post an update later today when the area reopens."

San Diego Mayor Todd Gloria said on Twitter that the city's firefighters, lifeguards, and police assisted the US Coast Guard and Port of San Diego Harbor Police in the rescue effort.

"I ask San Diegans to keep the boat's passengers in your prayers," he noted.

Four days earlier, the US authorities detained 21 Mexican nationals after a panga boat was stopped off about 11 miles west of the Point Loma shoreline, reported KGTV, an ABC-affiliated television station.

"We've seen a dramatic increase in the number of maritime smuggling attempts recently," Aaron Heitke, chief patrol agent of the US Border Patrol's San Diego Sector, was quoted as saying by the news outlet.

The US Border Patrol has documented 157 maritime smuggling events in the San Diego area in this fiscal year, KGTV reported, citing officials.