One of the sons of imprisoned drug lord Joaquin "El Chapo" Guzman (pictured) is among the half-dozen men abducted by gunmen at a restaurant in the Mexican beach resort of Puerto Vallarta.
Jalisco state Attorney General Eduardo Almaguer said 29-year-old Jesus Alfredo Guzman Salazar was among those taken, though the authorities still had not received any missing person complaints.
"The person by the name of Jesus Alfredo Guzman Salazar, age 29, is the son of Joaquin Guzman Loera," Mr Almaguer said at a news conference.
His abduction "has been confirmed by what was found in the vehicles and what security agencies found and the forensic examinations performed".
Earlier in the day, Mr Almaguer had said authorities were trying to confirm whether another Guzman son, Ivan Archivaldo Guzman, was among those abducted.
He said later that authorities had identified four of the six men marched out of the upmarket restaurant by seven armed assailants. He did not say whether Ivan could be one of the two still not identified.
Mr Almaguer said officials have identified the kidnappers as belonging to the Jalisco New Generation cartel, the dominant criminal group in the state.
The victims are all believed to be the rival Sinaloa cartel headed by Guzman in the neighbouring state of Sinaloa.
Experts have said Ivan Archivaldo assumed control of parts of the cartel's drug operations after his father was re-arrested in January.
The US Treasury Department designated both brothers in 2012 under the Foreign Narcotics Kingpin Designation Act as assisting their father in drug trafficking.
Jesus Alfredo, along with his father and other Sinaloa cartel leaders, were indicted in court in Chicago in 2009 on drug trafficking charges.
After reviewing security camera footage, Mr Almaguer said that besides the restaurant's staff, there were nine women and seven men dining together when the gunmen burst in early on Monday.
"The subjects enter, control the diners, separate the women to a side and violently take them (the men)," he said.
"They resisted; however, these criminals who arrived did it with a certain violence with long guns."
Mr Almaguer said one of the men managed to escape. He said authorities also had not located any of the women who were left behind.
"We have not received a single report from anyone to help locate these people who were (kidnapped)," Mr Almaguer added. He said the authorities had also not heard of anyone demanding a ransom.
The Jalisco cartel has grown quickly to rival Guzman's Sinaloa cartel as the most powerful of Mexico's drug gangs.
Experts said the kidnapping could be the latest in a string of attacks against Guzman's family, perhaps suggesting the drug lord has lost control of his cartel.
He purportedly ran affairs from prison until his second escape last year, but since being recaptured had been kept under stricter security measures.
In June, local media reported that an armed gang broke into the home of Guzman's mother in Sinaloa and taken vehicles and other goods.