Three violent prisoners are on the run after making a dramatic escape from a Californian maximum security jail.
Jonathan Tieu, Hossein Nayeri and Bac Duong fled the prison in Southern California after cutting through steel bars and abseiling from the roof on a makeshift rope.
One of the men is a suspected killer, while another is accused of cutting off a man's penis.
Orange County sheriff's Lieutenant Jeff Hallock warned the public to "expect the worst" if they were confronted by the criminals.
"It was very well-thought-out and planned," he told a news conference on Saturday.
The inmates were last seen at 5am on Friday at the Orange County Central Men's Jail in Santa Ana, about 40 miles southeast of Los Angeles.
They could have made their escape any time between then and late Friday night, authorities said.
They were last seen wearing orange prison jumpsuits at the 5am inmate count, and their absence was not noted until the 8pm count, Lt Hallock said.
"The inmates cut through half-inch steel bars to facilitate their escape," he said.
He added that before the nighttime count, there was a disturbance at the jail that may have been part of the escape plan.
It slightly delayed the discovery that the men were missing, he said.
Their escape is the first from the 900-inmate facility in 20 years.
Tieu, 20, has been in prison since October 2013 on charges of murder, attempted murder and shooting at an inhabited dwelling. His case is believed to be gang-related.
Nayeri, 37, had been in the jail September 2014 after being charged with kidnapping, torture, aggravated mayhem and burglary.
Along with three other men, Nayeri stands accused of kidnapping a California marijuana dispensary owner in 2012.
The men allegedly drove the dispensary owner to a desert spot where they believed he had hidden money and then cut off his penis.
After the crime, Nayeri fled the U.S. to his native Iran, but was arrested in Prague in November 2014 while changing flights from Iran to Spain to visit family.
The third fugitive, 43-year-old Duong, was imprisoned last month on an array of charges including attempted murder, assault with a deadly weapon, shooting at an inhabited dwelling.
It was unclear whether the men were armed but they should be considered very dangerous, Lt Hallock said.
"I think the public should expect the worst if they're encountering them and call 911 and allow the professionals to respond," he warned.
