Three bodies found tossed in a well in a remote region of Mexico have been confirmed as two Australian brothers and the American they were travelling with.

Mexican authorities confirmed on Monday (Australian time) that the bodies belonged to Perth brothers Callum, 33, and Jake Robinson, 30, and their American friend Jack Carter Rhoad, 30.

The Baja California Attorney-General’s Office confirmed their identification after a regional official earlier revealed the men’s parents Martin and Debra Robinson, had arrived in Mexico. They are reported to have viewed their sons’ bodies.

Authorities said the trio on a surfing trip to Mexico was killed by thieves, probably to steal their vehicle for its tyres.

Their corpses were then dumped into a remote, 15-metre-deep well, where they were found at the weekend.

The well also contained a fourth cadaver that had been there much longer. It is believed to be the body of the farmer who owned the land. He had been missing for several weeks.

The brothers and Rhoad went missing last weekend during a camping and surfing trip, posting idyllic photos on social media of waves and isolated beaches along a stretch of coast south of the city of Ensenada.

Baja California Attorney General Maria Elena Andrade Ramirez described the moments of terror that ended their trip. She said the killers drove by and saw the foreigners’ Chevrolet Colorado ute and tents.

“They approached, with the intention of stealing their vehicle and taking the tyres and other parts to put them on the older-model pickup they were driving,” she said.

“When they [the victims] came up and caught them, surely, they resisted.

“These people, the assailants, took out a gun and first they killed the one who was putting up resistance against the vehicle theft, and then others came along and joined the fight to defend their property and their companion who had been attacked, and they killed them too.”

Andrade Ramirez said the killers then took the bodies to “a site that is extremely hard to get to” and dumped them into a well they apparently were already knew of. She said investigators had not ruled out the possibility the same suspects also dumped the first, earlier body.

“They may have been looking for trucks in this area,” Andrade Ramírez said.

The site where the bodies were discovered is near the township of Santo Tomás and also near the remote seaside area where the missing men’s tents and vehicle were found last Thursday.

From their last photo posts, the men’s trip looked perfect. But even experienced local expats have questioned whether it is safe to camp along the largely deserted coast.

The moderator of the local Talk Baja internet forum, who has lived in the area for almost two decades, wrote in an editorial on Saturday that “the reality is, the dangers of travelling to and camping in remote areas are outweighing the benefits”.

Baja California prosecutors had said they were questioning three people in the case.

Three Mexicans, Jesús Gerardo Garica Cota (alias El Kekas), his partner Ari Gisel García Cota, and his brother Christian Alejandro Garcia, have since been charged with forced kidnapping.

There are multiple reports at least one is likely to be charged with murder.

Last week the missing Australians’ mother, Debra Robinson, posted on a local community Facebook page an appeal for help in finding her sons.

Robinson said Callum and Jake had not been heard from since April 27. They had booked accommodations in the nearby city of Rosarito.

Robinson said Callum was diabetic. She also named the American with them as Jack Carter Rhoad, although the US State Department is yet to confirm his details.

Treasurer Jim Chalmers offered his condolences to the Robinson family on Monday, saying the whole country mourned with them.

“We can only imagine what this ordeal has been like for them and for the loved ones of Callum and Jake,” he said.

“It has been an absolutely horrendous, absolutely horrific ordeal and our thoughts are with all of them today.”

In 2015, two Australian surfers, Adam Coleman and Dean Lucas, were killed in Mexico’s western Sinaloa state, across the Gulf of California from the Baja California peninsula.

Authorities said they were victims of highway bandits. Three suspects were arrested in that case.

-with AAP