LOS ANGELES (Reuters) - Authorities pressed on through the third day of an intense Southern California manhunt on Sunday for an accused killer and two other inmates charged with violent felonies who broke out of an Orange County jail through a plumbing tunnel, officials said.

The escaped prisoners were identified as Hossein Nayeri, 37, Jonathan Tieu, 20, and Bac Duong, 43, who were housed together in a 68-man dormitory-style unit of the jail before slipping away early on Friday morning, Orange County Sheriff’s Department officials said.

“The three escapees ... are dangerous criminals,” Sheriff Sandra Hutchens said in a statement.

The trio cut through a steel grate inside their unit, climbed through a plumbing conduit and up to the jailhouse roof, then used bedsheets to lower themselves four stories before disappearing, according to sheriff’s spokesman, Lieutenant Jeff Hallock.

Video surveillance footage examined later showed a glimpse of the men before they were last seen inside the jail earlier that morning, Hallock said.

As of Sunday night, local, state and federal authorities searching for the three men were pursuing a number of leads but had received no reports of sightings or other “significant” clues to their whereabouts, he said.

Their “sophisticated” escape was apparently planned for weeks or months and marked the first breakout from the jail since 1989, the lieutenant said.

The jail, housing about 900 inmates, is located in the Orange County seat of Santa Ana, about 9 miles south of Anaheim, the Los Angeles-area suburb best known as home to Disneyland.

Hallock said the men could be armed but declined to disclose what mode of transportation they may be using. He also said authorities are investigating whether the prisoners had help inside or outside the jail.

The jailbreak recalled the escape of two convicted murderers from a maximum-security prison in upstate New York last year. A three-week manhunt ended with the fatal shooting of one of the inmates and the capture of the second a mile from the Canadian border.

Nayeri, an Iranian national, is one of four people accused of kidnapping and torturing a marijuana dispensary owner, the Orange County Register reported. He had been jailed without bond since September 2014 after being arrested by the FBI in Prague.

Tieu has been held at the facility since October 2013, charged with a murder that authorities believe was gang-related. Duong was jailed without bond last month, charged with attempted murder and other offenses.