A pontoon boat carrying 20 people, most of them family members participating in a memorial service, sank near San Francisco's Alcatraz Island on Tuesday afternoon, leaving one person dead and rescue crews searching through the night for additional passengers.

What Happened

The emergency call came in just after 3:30 p.m. Tuesday, according to San Francisco Fire Lieutenant Mariano Elias, after a 50-foot, three-deck pontoon "pleasure boat" began taking on water roughly 600 yards from Alcatraz Island. San Francisco Fire Chief Dean Crispen said crews arriving on scene found the vessel almost fully submerged, its motor still running and leaking fuel. The boat, believed to have launched near the St. Francis Yacht Club, was reportedly based out of Stockton. Officials initially received reports describing the incident as a fire, but Crispen later said "we now don't have any evidence of that."

Witnesses described rough seas in the area at the time. "The reports we've had from witnesses was that there were rough seas and the vessel began to take on water and was turned over in the bay," Crispen said. Longtime San Francisco Bay sailor Mike Peterson told reporters incidents like this are rare for vessels of that size: "It would take something happening very rapidly to cause a boat like that to go down and people like that to end up in the water."

A Bystander's Account

Aaron Anfinson, captain of a nearby boat called the Bass-Tub, told the San Francisco Chronicle his vessel was carrying guests toward the Golden Gate Bridge through "pretty windy, a little choppy" waters when they came upon the sinking pontoon. By the time they reached it, Anfinson said, the flames some had reported were out, but the boat was going down — some passengers were already in the water while others remained aboard. Anfinson's crew handed out life jackets and helped pull people from the water, including one woman with a head injury. "We figured we would get her first," he said, describing the effort to lower a swim ladder and throw a life ring to help her aboard. "It was scary," Anfinson said. "I don't want to see anybody in that situation."

The Toll So Far

According to the most recent figures from authorities, 20 adults were aboard the vessel when it sank, most of them family members taking part in a memorial service. Sixteen people were rescued, one person died after being pulled from the frigid water alive but succumbing shortly after, and — as of the most recent reporting — three people remained missing. A dog aboard the vessel also died. Three injured passengers were transported to the hospital in stable condition and were expected to be released the same day. San Francisco Police Marine Unit members reportedly found one man in the water in "severe distress" upon arrival. "Our understanding was there was some kind of memorial service that they were engaging in. That's why they were using this particular vessel," Crispen said.

The Search Effort

The search for the missing passengers, involving divers, helicopters, and roughly 11 vessels — including the U.S. Coast Guard, San Francisco Police and Fire marine units, the Oakland Police Department's marine unit, and private boats — was expected to continue through the night, focused on open ocean west of the Golden Gate Bridge. "Our standard operating procedure is to continue to search as long as it's safe enough for us to search," Crispen said. "This search will go on for some time." All those rescued were taken to Gashouse Cove Marina, and officials set up a family reunification center at Fort Mason, west of Fisherman's Wharf.

About the Location

Alcatraz Island, once home to the notorious federal prison that closed in 1963, sits about a mile offshore in San Francisco Bay and is now a national park and popular tourist destination. The waters around it are known for strong currents and frequently windy, choppy conditions that attract sailboats and other recreational vessels, but which can also make for hazardous boating.

What's Next

Authorities have not yet determined the precise cause of the sinking, and the search-and-rescue operation for the remaining missing passengers was ongoing as of the latest reports. This remains a developing story, and further details are expected as investigators piece together what caused the vessel to capsize.