SANTA ANA (California) • A manhunt spanning Southern California was under way for three inmates, described as "very dangerous", who escaped from a maximum-security jail in Orange County using tools to cut through steel bars and then rappelling from the jail's roof with makeshift ropes made of linen.

The authorities said on Sunday that they believed the inmates - Hossein Nayeri, 37, Jonathan Tieu, 20, and Bac Duong, 43 - escaped from the Orange County Central Men's Jail here soon after the 5am head count on Friday. Their absence was not discovered until the 8pm head count that day, the Orange County Sheriff's Department said.

Tieu has been charged with murder and attempted murder. His case is believed to be gang-related, and he had been held since 2013 on a US$1 million (S$1.43 million) bond.

Nayeri has been charged with kidnapping and torture in connection with the abduction of a marijuana dispensary owner in 2012. He is accused of being one of four men who took the dispensary owner to a spot where they believed he had hidden money, and cut off his penis, the authorities said. Nayeri then fled to his native Iran, before being recaptured in the Czech Republic and extradited to the United States. He had been held without bond since 2014.

Duong has been charged with attempted murder and had been held without bond since last month.

Sheriff Sandra Hutchens, the county's top law enforcement official, issued a stern warning to the public on Sunday: "Presume that they are armed, and do not approach them."

The three men were housed in a large dormitory-style cell, which can hold more than 60 inmates.

"It seems that the inmates cut through half-inch steel bars to facilitate their escape," Lieutenant Jeff Hallock of the Sheriff's Department said.

He added that evidence suggested they had also "cut their way through the plumbing tunnels and ultimately gained access to an unsecured area of the roof".

NEW YORK TIMES