A suspected smuggling boat capsized off the coast of San Diego, California on Sunday morning leaving three dead and at least 20 people have been rushed to hospitals, as per media reports. 

Monica Munoz, a spokesperson for the San Diego Fire Rescue Department told reporters that the department received reports of an overturned vessel at 1.27 pm ET, reported CNN. The accident happened near the Cabrillo National Monument in Point Loma.

The people onboard were likely trying to enter the United States, illegally, reported AFP. 

Lifeguard chief for San Diego, James Gartland, explained that incident. He told reporters that it seems like the vessel hit the reef, broke and 30 people "came out of the vessel. This was a mass rescue operation that turned into a mass casualty incident."

San Diego Fire-Rescue lifeguard Lt Rick Romero said that by the time first responders reached, the 40-foot cabin cruiser had already broken apart. 

"Our goal was just to rescue everyone we could. Conditions were pretty rough -- 5-6 feet of surf, windy, cold, the water's around 60 degrees so you get hypothermic pretty quickly," he said. 

According to Romero, there were a total of 30 people on the boat. While most of them made it to the shore, six people had to be rescued after they were pulled into the water by the sea current, reported CNN. 

AFP reported that Jeffery Stephenson of the Customs and Border Protection Public Affairs Office said, "It was a smuggling vessel. Border Patrol agents are with a man we believe was the operator. Smugglers don't care about the people they're exploiting."

"All they care about is profit. They had inadequate safety equipment and obviously this vessel was severely overcrowded," he added. 

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 Supervisor and border patrol agent, San Diego sector of US Customs and Border Patrol said, "Every indication, from our perspective, is that this was a smuggling vessel used to smuggle migrants into the United States illegally." 

"We've seen a dramatic increase in the number of maritime smuggling attempts recently. 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," said Chief Patrol Agent Aaron Heitke with CBP's San Diego sector.

The San Diego Fire Rescue Department tweeted updates about the rescue mission.

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SDFC wrote, "24 persons were on board. Many patients transported to hospitals. @USCG Fed Fire & many other agencies assisting."

Most of the people taken to hospitals were "non-emergent," but three people were believed to be in "somewhat to very urgent status," Munoz said. 

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Todd Gloria, the mayor of San Diego, asked citizens to "San Diegans to keep the boat's passengers in your prayers."

People hurt in the accident were taken to local hospitals "including Sharp Memorial, Palomar Medical Center West, Alvarado, UCSD Medical Center (Hillcrest), Grossmont Hospital, Kaiser Clairemont Mesa, Kaiser Zion and Paradise Valley Hospital," said the department.