Mexican and U.S. search teams continue looking for "between five and seven people" missing in the capsizing of the charter fishing boat Erik over the weekend in the Sea of Cortez, Baja California Gov. Jose Guadalupe Osuna said.

A total of 35 people - 18 tourists and 17 crew members - have been rescued since the shipwreck off San Luis, an island in Baja California, which is in northwestern Mexico.

One person, Leslie Lee, died in the shipwreck, the governor said, without releasing the victim's nationality.

The boat was carrying American tourists and a Mexican crew, press reports said.

"Priority number one" is to find the missing because the situation becomes more dire "with every minute that passes," the governor said in a joint press conference Tuesday with U.S. Consul General Steve Kashkett.

Officials are also looking to clear up "the causes of the accident and the conditions in which the fishing boat was operating," Osuna said.

"Two helicopters and a Hercules plane (from the United States) are flying over the area and assisting in the work headed up by Mexico's Navy Secretariat," the governor said.

Mexican rescuers have the support a plane, two helicopters and three Mexican navy ships.

The passenger list is incomplete and it is not known how many people are actually missing, the governor said, adding that one person apparently ended up not sailing on the Erik.

There are unconfirmed reports that a U.S. plane brought in a robot to search the wreck for bodies.

The boat sank about 108 kilometers (67 miles) offshore, Mexican officials said.

Gary Wong, one of the survivors, said he regretted convincing two of his brothers, one of whom is missing, to go fishing with him.

"By this time, the most likely thing is that he died," Wong said.

"We are not going home without his body," Wong said, adding that he had made the same trip the past two summers and never imagined that an accident like this could happen.

Officials have not said what caused the shipwreck, but there are reports that bad weather, including heavy rains and high seas, may have been the reason the Erik went down.

The 35-meter (115-foot) boat offered sports fishing and commercial charters lasting several days and specializing in dolphin, which are abundant in the Sea of Cortez.