(CNN) The person believed to have been operating a suspected smuggling vessel that overturned off the coast of San Diego on Sunday, killing three people, is in custody.
There were 32 people aboard the 40-foot cabin cruiser, including the captain, when the boat hit the reef and broke apart near the Cabrillo National Monument in Point Loma around 10:30 a.m. PT, authorities said in an update Monday.
Twenty-nine people survived, officials said. Among five remaining in the hospital, one is in critical condition, according to a news release from the US Coast Guard 11th District PA Detachment San Diego.
"Every indication from our perspective is that this was a smuggling vessel to smuggle migrants into the United States illegally," US Customs and Border Protection (CBP) Supervisory Agent Jeff Stephenson said at a news conference Sunday.
In Monday's release, US Customs and Border Patrol said that 27 of the surviving passengers were Mexican nationals who did not have legal status to enter the US.
One of the Mexican nationals was an unaccompanied 15-year-old boy, CBP said. The other Mexican nationals ranged in ages between 18 and 39.
Another passenger was from Guatemala, with no legal status in the US, according to CBP.
The final person, the captain of the boat, is a US citizen who remains in US Border Patrol custody. His name has not been released.
During Sunday's press conference, Brandon Tucker, CBP deputy director of air operations for the San Diego Air and Marine Branch, said the captain of the suspected smuggling boat was"a bit out of it, but he is speaking to agents on scene."
Search efforts were suspended Monday, CBP said.
Multiple agencies responded to the area after the call came in for a multiple casualty incident, including the Coast Guard, lifeguards, and firefighters.
Stephenson said the boat was "severely overcrowded" when the incident occurred.
Six people were rescued from the water and others were able to walk or swim to shore on their own, Lifeguard Lt. Rick Romero with San Diego Fire-Rescue said during a news conference Sunday afternoon.
Romero said injuries ranged from hypothermia to physical injuries sustained when the boat broke apart.
"Conditions were pretty rough, five to six feet of surf, windy, cold, water is around 60 degrees, so you get hypothermia pretty quickly," Romero said.
"The boat was on the reef, bouncing back and forth, and then just slowly disintegrated into a bunch of pieces, so there's no boat there, it's all debris."
While there were life jackets aboard the vessel, it's unknown how many passengers or crew were using them, he said.
Romero also said that the boat did not have a manifest, so he couldn't say if there were children on board at the time the boat overturned.
The 40-foot vessel that struck the reef Sunday is larger than the smuggling boats CBP typically encounters off the Southern California coast, according to Tucker.
"We're assuming that it was illegal migration, but generally they are smaller, in the 20 to 30-foot range, generally about 20-plus migrants," he said. "This one was a bit larger than normal, but for overcrowding on these vessels, the unsafe conditions on these vessels, it's the same, it's just slightly larger."
In a news release issued on Saturday, CBP said it was "ramping up operations to disrupt maritime smuggling off the coast of San Diego this weekend."
"We've seen a dramatic increase in the number of maritime smuggling attempts recently," Chief Patrol Agent Aaron Heitke with CBP's San Diego sector said in the news release. "All of these illegal crossings at sea are inherently dangerous, and we have seen too many turn from risky to tragic as smugglers sacrifice the safety of those on board for the sake of profits."
A small wooden "panga" type vessel was interdicted by CBP off the coast of Point Loma on Thursday with 21 people on board, officials said in the news release.
"When we interdict suspect vessels, we routinely find unsafe conditions, with people overcrowded into small boats without necessary safety equipment," N. Michael Montgomery, director of CBP's air and marine operations in San Diego, said in the release.
"The individuals on board these small vessels, trying to enter the U.S. illegally, frequently are not told of the dangers they will face on their journey and are not prepared. They will end up far out to sea, in a small boat without adequate food, water, safety gear, or protection against the elements."
Correction: The Coast Guard has revised its information regarding the number of people on board and those who died. This story has been updated to reflect the corrected numbers.