Eight American vacationers are presumed to have drowned after a sports fishing charter capsized in a storm and sank off Mexico's Baja California peninsula, authorities said on Monday.

The 115-foot (35-meter) boat Erik left San Felipe on the Sea of Cortez, a haven for windsurfers and sports fishermen, on Saturday for a six-day fishing trip with 43 people on board, including 27 American tourists.

But on its first night out of port, the Erik was struck by an electrical storm and capsized early on Sunday, port and navy officials said.

After searching for almost 24 hours, local rescue officials had found one body and said they had given up hope of finding seven missing people alive. Divers had been brought in to aid in the search.

We have changed the operation, now we're focusing on recovering ... people, but not alive, said Alfredo Escobedo, the director of emergency services in Baja California state.

The confirmed fatality and all the missing were U.S. citizens, San Felipe port official Dora Winkler said.

Mexican authorities said the survivors had been rescued by navy teams and locals after the fishing boat's cook and two passengers were saved by local fishermen, who had raised the initial alarm.

The boat was found around 87 miles (140 km) south of San Felipe, a popular holiday and fishing resort located south of Mexicali.

Local boat operators cater to American retirees and other tourists who flock to the region for inexpensive salt-water fishing. Loyalists boast a sea teaming with yellowtail, sea bass and cabrilla.

According to an Internet advertisement, the Erik, available for six-day charters from $995 per person, had been operating in the Sea of Cortez since 1989 and slept up to 42 guests.