Two bank robbers have pulled off a daring escape using a makeshift rope to scale 20 floors of a prison in Chicago.
Investigators found a broken window in the men's cell and the window bars hidden inside a mattress.
Fake bars were recovered and each man's bed had been stuffed with clothing and sheets to resemble a body, the FBI said.
Joseph Banks, 37, and Kenneth Conley, 38, had been gone for more than three hours before officials realised.
FBI officers believe it was a meticulously planned escape from the 27-storey Metropolitan Correctional Centre that came a week after Banks made a courtroom vow of retribution.
Both men are facing long prison sentences, and the FBI said they should be considered armed and dangerous.
Elite police teams stormed at least one home in the Tinley Park suburb of Chicago, where evidence suggested both men had been just hours earlier.
Some schools went on lockdown after being inundated with calls from nervous parents.
Mike Byrne, a superintendent in Tinley Park, said: "Our parents are so emotionally charged right now because of the school shootings in Connecticut."
The prison is one of the only skyscraper jails in the world and experts say its triangular shape was meant to make it easier to guard.
The facility was built almost 40 years ago. There has been only one other escape from the building, in the mid-1980s.
Both Banks and Conley were wearing orange jumpsuits but police believe they may have quickly changed into white T-shirts, grey tracksuits and white trainers.
Banks was convicted last week of robbing two banks and attempting to rob two others. Authorities say he stole almost \$600,000 (£369,000) - most of which is still missing.