MEXICO CITY - The three dead bodies found in Mexico's Baja California state are highly likely to be the American and two Australian tourists who went missing last week, a senior official from the region said on Saturday.

Mexican authorities are conducting forensic tests after finding the bodies on Friday in a well following a days long search for Australian brothers Callum, 33, and Jake Robinson, 30, as well as American Carter Rhoad, 30.

The trio were on vacation surfing near the popular tourist town of Ensenada, about 90 minutes south of the US-Mexico border on the Pacific coast

The trio were on vacation surfing near the popular tourist town of Ensenada, about 90 minutes south of the US-Mexico border on the Pacific coast.

"All three bodies meet the characteristics to assume with a high degree of probability that they are the American Carter Rhoad as well as the Robinson brothers from Australia," said Baja California's state Attorney General Maria Elena Andrade.

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Andrade said that while the three bodies were found in an advanced state of decomposition at the bottom of a well more than 15 meters (50 ft) deep, "some physical descriptions give us that high probability".

Baja California is one of Mexico's most violent states, although the Ensenada area is considered safer. The US State Department advises Americans to reconsider travel to the state due to crime and kidnapping.

The three surfers were last seen on April 27 and reported missing a couple of days later, when authorities launched a multi-day search with the help from the US Federal Bureau of Investigation (FBI).

Three people have so far been arrested, officials say. A burnt-out vehicle believed to have been used by the three surfers was also found in the area.

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Mexican authorities' preliminary hypothesis is that the arrested individuals attempted to carjack the foreigners and when the surfers resisted they were shot and their bodies dumped in a well, Andrade said.

A fourth male body was discovered in the well, though that corpse had been there for longer and is not believed to be linked to this case, Andrade added.