Infamous drug lord Joaquin "El Chapo" Guzman has escaped — for the second time in his life — from a maximum security prison in Mexico.

Guzman, a former top boss of the powerful Sinaloa Cartel, was last seen at 8:52pm in a section of shower stalls at the Altiplano prison, about 56 miles west of Mexico City. A manhunt is underway, officials said.

In a press conference early Sunday morning, Monte Alejandro Rubido, Mexico's national security commissioner, said Guzman apparently escaped through a tunnel opening that was said to be only 50 centimeters in diameter. That tunnel led to another passageway that Rubido described as being more than a mile long, containing lighting and a ventilation system, as well as a motorcycle built onto rails to move building materials.

The second tunnel was described as being 1.7 meters high, or 5 feet, 6 inches — just tall enough for El Chapo, whose nickname means "Shorty," to walk. It reportedly opened up into an abandoned construction site.

Authorities said 18 prison employees and officials have been detained and are being questioned in Mexico City.

"I am just stupefied," Alejandro Hope, an independent editor and security analyst, told VICE News. "With a figure of this caliber, they were not ready."

Initial reports said that the government halted flights at Toluca International Airport, which is only about 25 miles from the Altiplano prison. But when reached by VICE News, the airport's director of operations said the facility had received no instructions to cancel or delay flights in an effort to prevent Guzman from boarding a plane.

"We never closed the airport and it's been operating as normal," director Miguel Perez said. "Our security is a little raised, but overall, all normal."

El Chapo now has a history of busting out of Mexican prisons. He was first caught by authorities in Guatemala in 1993, extradited, and sentenced to 20 years in prison on drug-related charges. He eventually escaped from Puente Grande, another Mexican maximum security prison in western Jalisco state, in 2001 with the help of prison guards. Legend has it that El Chapo was wheeled out of Puente Grande hidden in a laundry cart.

In January, former Mexican Attorney General Jesus Murillo Karam boasted that there was "no way" Guzman could escape custody again. Karam later resigned amid criticism for his handling of the case of the missing 43 students in Guerrero.

Guzman, who is believed to be around 56 years old, wasn't recaptured until February 2014. During his first stint as a fugitive, he rose through the ranks of the Sinaloa Cartel to become one of the most feared and powerful kingpins in the Mexican underworld. He achieved international notoriety when Forbes magazine listed his fortune at more than $1 billion. He has also been blamed for ordering some of the worst bloodshed in Mexico's ongoing drug war, a conflict that has claimed more than 100,000 lives in the last decade.

Mexican and US authorities finally caught up to El Chapo in the Sinaloa beach resort city of Mazatlan on February 22, 2014. He was captured without a shot being fired in a modest beachside high-rise, where he had been hiding with his wife and twin daughters. In the preceding days, Guzman narrowly avoided arrest by escaping through hidden tunnels that led from beneath a Jacuzzi in one of his homes in Culiacan, Sinaloa.

This gives an idea of quite how long the tunnel is. Must have been building it since Chapo's arrest in Feb 2014 — Gabriel Stargardter (@gabstargardter)July 12, 2015

El Chapo faces a number of organized crime and drug trafficking charges in the United States, but Mexican officials said previously that he would have to finish his sentence in Mexico before they would extradite him. Other top drug lords have been extradited to the US, including Osiel Cárdenas Guillén, the former leader of the Gulf Cartel, who is now housed in the "Supermax" prison in Colorado known as the Alcatraz of the Rockies.

The escape is an embarrassment for the administration of President Enrique Pena Nieto, which has touted its ability to capture cartel bosses, including the leaders of the Los Zetas, Juarez, and Beltran Leyva cartels. Several of those captured cartel leaders were housed with El Chapo in Altiplano, which had been considered the most secure facility in Mexico.

The president and top members of his cabinet were flying to Paris for a state visit when El Chapo escaped, resulting in mocking jokes from Mexicans on social media about the government's ability to take Guzman to justice. After touching down in Paris, Interior Minister Miguel Angel Osorio Chong immediately traveled back to Mexico, reports said.

Even after Guzman's 2014 capture, business continued as usual for the Sinaloa cartel. Top leaders Ismael "El Mayo" Zambada, Juan José "El Azul" Esparragoza, and Fausto Isidro "El Chapo Isidro" Meza Flores have remained free, building a global empire that stretches from Europe to Australia.

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_The Associated Press contributed to this report. _