Mexico government says it has launched an all-out manhunt for drug lord Joaquin "El Chapo" Guzman, who has escaped from a maximum-security prison through a 1.5km tunnel, in his second jail break in 14 years.
President Enrique Pena Nieto reacted to the incident by saying he wanted a full investigation into the jailbreak to uncover whether any public officials helped the head of the notorious Sinaloa Cartel.
"This represents without a doubt an affront to the Mexican state," Pena Nieto said while on a previously scheduled trip to France. "But I also have confidence in the institutions of the Mexican state ... that they have the strength and determination to recapture this criminal."
With the brazen escape, Guzman has done what Mexican authorities promised would not happen after his re-capture last year - slip out of a maximum security prison again.
After security cameras lost sight of Guzman, guards went into the cell and found a hole 10 metres deep with a ladder, National Security Commissioner Monte Alejandro Rubido said.
The gap led to the 1.5km tunnel with a ventilation and light system, Rubido said, adding that its exit was in a building that was under construction in central Mexico State.
A motorcycle on a rail system was found in the tunnel and is believed to have been used to transport tools and remove earth from the space, which was 1.7m high and around 80cm wide.
Eighteen employees from various parts of the Altiplano prison have been taken in for questioning, the security commissioner, Monte Alejandro Rubido, said in a news conference.
Guzman had been in prison since February last year.
In more than a decade on the run, he transformed himself from a middling Mexican capo into arguably the most powerful drug trafficker in the world.
His cartel has been heavily involved in the violent drug war that has torn through parts of Mexico for the last several years.
At one point, his fortune grew to more than $1bn, according to Forbes magazine, which listed him among the "World's Most Powerful People" and ranked him above the presidents of France and Venezuela.
In 2013, the financial magazine took Guzman off the list, saying it was likely security expenses had cut into his trove.
His Sinaloa Cartel took over much of the lucrative trafficking routes along the US border, including cities such as Tijuana and Ciudad Juarez.
Guzman's play for power against local cartels caused a bloodbath in Tijuana and made Juarez one of the deadliest cities in the world.