Shocking update after two Australians and their American friend vanish without a trace while in Mexico

A woman and two men have been arrested during the search for three foreign missing surfers in Mexico who failed to return to their Airbnb after a surfing trip.

Jake, 30, and Callum Robinson, 33, from Perth, Australia, and their friend Jack Carter Rhoad, 30, from San Diego, vanished five days ago in the Baja California region near Ensenada on Mexico's north-west coast.

After sharing regular social media posts about the first two days of their trip, they trio have not been heard from since Saturday.

A 23-year-old Mexican woman has been arrested in connection to the case, Baja California Attorney General María Elena Andrade Ramírez told reporters.

She was discovered in possession of a mobile phone belonging to one of the brothers, along with methamphetamine.

Two men, also Mexican, were arrested alongside her, Ms Ramírez said.

It is understood police were able to make the arrests after one of the brothers' mobile phones was turned back on, and pinged a local mobile tower.

Jake (left) and Callum Robinson (right) have not been heard from for days after going missing on a surfing trip to Mexico (pictured with their parents)

Jack Carter Rhoad, 30, from San Diego, is also missing

According to local media, blood was discovered at three abandoned tents where the brothers and their friend were believed to be staying before they vanished.

A burnt-out white Chevrolet Colorado pickup truck was found on a ranch in the Santo Tomás area after the ranch manager called 911 on Thursday (local time), according to local media TalkBaja.

A check of the vehicle's VIN reportedly identified it as belonging to one of the three missing surfers.

The men were said to be driving a Chevrolet Colorado with the Californian number plate 70189W1.

The three tents were discovered south of the Ensenada region and local authorities have searched hundreds of square kilometres of land in the surrounding area.

A woman and two men, all Mexican, have been arrested in connection to the case, Baja California Attorney General María Elena Andrade Ramírez (centre) told reporters

According to local media, blood was discovered at three abandoned tents where the brothers and their American friend were believed to be staying before they vanished. A truck, said to belong to either Jake or Callum, was also found burnt out at a nearby farm (pictured)

Former FBI agent Phil Andrew (right) pinpointed the most worrying detail about the police investigation so far: the fact one of the men's phones was found in the hands of another person

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Ms Ramírez said 'very important time was lost' as police only launched their search for the three men after seeing reports of their disappearance on social media.

'A working team [of investigators] is at the site where they were last seen, where tents and other evidence was found that could be linked to these three people we have under investigation,' Ms Ramírez said on Thursday.

'There is a lot of important information that we can't make public.'

Prime Minister Anthony Albanese said on Friday the Department of Foreign Affairs had been in touch with the brothers' family.

'This is a really concerning situation,' he said.

'Our embassy in Mexico is working with local authorities as well to try to ascertain what has happened here.'

'We hope that these brothers are found safely but there is real concern about the fact that they've gone missing.'

'Their mother is obviously very distressed about this and we just hope for a positive outcome.'

The brothers' family is said to be 'frantically' trying to get a flight to Mexico, reports 7News.

It comes as a former FBI agent pinpointed the most worrying detail about the police investigation so far: the fact one of the men's phones was found in the hands of another person.

'This additional information that their phone was in a third person's hands, that creates concern,' Phil Andrew told Sunrise on Friday morning.

'They're in an area that is difficult to police and very remote, and there are reports of increased level of crime there.'

When asked what was 'most likely scenario' for the men, Mr Andrew said it was safe to assume the trio met with foul play.

He added the likelihood of the incident being a kidnapping was diminishing the more time passes without any 'sort of demand' being made.

Debra Robinson appealed for help from the public in the search for her sons on Thursday 

A woman has reportedly been arrested during the search after she turned on a mobile phone that belonged to one of the brothers (Jake, left and Callum, right, with their parents)

Jake and Callum are understood to have gone missing from the Baja California region near Ensenada

Earlier, Jake and Callum's mother Debra Robinson issued an urgent plea for help to find her sons. 

'Reaching out to anyone who has seen my two sons,' Ms Robinson wrote on Facebook.

'They are travelling with another friend, an American citizen.

'They were due to book into an Airbnb in Rosarito after their camping weekend but they did not show up.'

Ms Robinson posted a photo which said her sons had gone missing around the Rosarito and Ensenada region of Baja California on Saturday morning.

Rosarito is a coastal city about an hour's drive north of Ensenada and a 45-minute drive south of the U.S. city of San Diego.

Ms Robinson said there was a medical concern as Callum is a type one diabetic.

She asked for anyone who had seen her sons or knew their whereabouts to contact her.

Lacrosse Australia issued a statement on social media expressing its concern over the whereabouts of Jake, Callum and their friend Jack Carter Rhoad.

It described Callum as an 'Australian lacrosse star'.

Callum, who was an avid social media user, is pictured here at a festival with a friend who is unconnected to his disappearance. He has been described as an 'Australian lacrosse star'

'We urge the Australian lacrosse community and our global lacrosse family to continue sharing the post from Callum's friends and family (located on the LA Facebook and Instagram story) in the hope that Callum, Jake and Jack are found safe and sound,' it said.

'Our thoughts are with the families and friends of the Callum, Jake and Jack during this incredibly stressful time.'

WA Premier Roger Cook said the situation was 'very worrying'.

'When we do send our young men and women overseas to enjoy that adventure holiday, they invite an element of risk and this is really quite distressing,' he said.

'I understand that one of the individuals has a medical condition that would need ongoing care, so I share concerns of all Western Australians in terms of their welfare.'

The Department of Foreign Affairs and Trade confirmed they were assisting the family.

'The Department of Foreign Affairs and Trade is providing consular assistance to the family of two Australians reported missing in Mexico,' a spokesperson said.

'Owing to our privacy obligations we are unable to provide further comment.'