People are being advised to ring 999 if they see escaped armed robber James Beeston.
Beeston, 28, originally from East End Park in Leeds, absconded from HMP Kirklevington Grange, in Yarm, on Tuesday.
Beeston was jailed for 10 years in 2013 along with three other men who committed a series of armed robberies across West Yorkshire.
It is believed he may be in the Leeds area and officers are trying to trace him.
West Yorkshire Police said: "Officers want to hear from anyone who has seen him or who has any information that could assist in tracing him.
"He is not thought to present any immediate risk to the public but anyone who sees him is advised not to approach him and to contact the police on 999 immediately."
During the court case at Leeds Crown Court in 2013, the jury was shown footage of the four men terrorising shop assistants and security guards with guns, knives, swords and baseball bats during a crime spree worth more than £200,000.
Their targets included the Gold Shop, Wakefield Road, Bradford as well as the Moreish Café, in Middleton, Leeds, where guards who had come to fill up a cash machine were targeted.
One had a knife held to his neck and another was attacked before the gang made off with £108,000 in cash.
Moving statements were read to the court on behalf of victims caught up in the attacks.
At the time Judge Geoffrey Marson, QC, said: "The psychological impact on some of these victims has been profound.
"Decent hard working people have had their lives blighted by these offences. For some of them life will never be the same again."