Police in Mexico are questioning 10 guards at a prison in the capital, Mexico City, after three high-profile inmates escaped.
The three, including a man suspected of being the financier for the sons of jailed drug lord Joaquín Guzmán, walked through five gates before driving away in an official car.
Three guards have reportedly confessed to helping the inmates escape.
All three prisoners were facing extradition to the US.
When guards did their morning check of the inmates they noticed that three were missing. Víctor Manuel Félix Beltrán, Luis Fernando Meza González and Yael Osuna Navarro had all escaped from the medium-security jail in Mexico City.
The fugitives passed through five gates to get to a courtyard where they boarded a prison car which whisked them away.
The gates had been installed at the medium-security jail after the three had been transferred there from high-security facilities.
An investigation is under way to find out whether the gates were left unlocked or whether the fugitives were provided with keys or instruments to open them.
Who are the fugitives?
Víctor Manuel Félix Beltrán is suspected of being an influential member of the powerful Sinaloa drug cartel, which was led by drug lord Joaquín "El Chapo" Guzmán until his capture and extradition to the US.
Félix Beltrán is suspected of handling the finances of three of Guzmán's sons. US prosecutors also accuse him of being a "high-level drug trafficker" who operated in the cities of Culiacán and Guadalajara and shipped cocaine to Chicago.
His father, Víctor Félix Félix, was "El Chapo" Guzmán's financier until the former was captured in 2011 and extradited to the US.
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Félix Beltrán was arrested at a luxury residential complex in Mexico City in October 2017. At first, he was held at the maximum-security Altiplano prison before being transferred in November 2018 to the Mexico City jail from which he escaped on Wednesday.
Meza González is accused of drug trafficking and Osuna Navarro is suspected of criminal association.
What has been the reaction?
The escape is yet another embarrassment for Mexico's prison system which became notorious for its corrupt guards after "El Chapo" managed to flee from Altiplano jail through an elaborate tunnel.
Mexico City Mayor Claudia Sheinbaum said there would be a thorough investigation.
A major manhunt is also under way in the city and surroundings.
The influence the Sinaloa cartel and the sons of El Chapo Guzmán wield became clear in October 2019 when fighting broke out in Culiacán between gang members and the security forces.
It was triggered by an attempt to detain, Ovidio Guzmán López.
The fierce gunbattle led Mexican President Andrés Manuel López Obrador to release Ovidio Guzmán López, arguing that keeping him in custody would have resulted "in a blood bath".