Santo Tomas - Three bodies were found in Mexico's Baja California state, the FBI said Friday, days after an American and two Australians went missing during a surfing trip in an area hit by cartel violence.

Authorities used a pulley system to hoist what appeared to be lifeless bodies covered in mud from a shaft on a cliff high above the Pacific, AFP journalists observed.

"We confirm there were three individuals found deceased in Santo Tomas, Baja California," a statement from the FBI's office in San Diego, California said without providing identities of the victims.

Australian brothers Jake and Callum Robinson and their American friend Jack Carter have not been seen since April 27.

They were on vacation near the coastal city of Ensenada in the northwestern state of Baja California.

But the brothers' mother, Debra Robinson, said in a Facebook post that they never arrived at their planned accommodation.

Santo Tomas, where the FBI reported the discovery of the three bodies, is about 30 miles southeast of Ensenada.

More than a dozen responders, including federal agents, state police, forensic experts, and military personnel, were at work Friday on the difficult-to-access cliff area.

Earlier in the day, navy personnel and officials from the state prosecutor's office searched a cliff area in Ensenada, according to city hall.

Baja California state authorities said Thursday that three Mexican nationals were being questioned in connection with the disappearances.

"A white pickup vehicle was located, as well as other evidence," the state prosecutor's office said in a statement.

The investigation was being coordinated with the FBI, as well as the Australian and US consulates, it added.

Baja California, known for its inviting beaches, is also one of Mexico's most violent states thanks to organized crime groups.

Two other Australian surfers, Dean Lucas and Adam Coleman, were murdered and their bodies burned while traveling in the northwestern Mexican state of Sinaloa in November 2015.

In March 2023, alleged members of the Gulf Cartel kidnapped four Americans in the northeastern city of Matamoros, across the border from Brownsville, Texas. Two of them were killed.

The spiral of violence engulfing Mexico has left more than 450,000 dead and more than 100,000 missing since the federal government launched a controversial anti-drug operation in 2006.