Four prison guards were being held hostage by convict Alket Rizai at Malandrino Prison in central Greece on Sunday morning.
The prison employees were taken hostage on Saturday night.
It appears that Rizai was attempting to break out of jail with two fellow inmates. He is said to be armed with sharp implements.
Police are in negotiations with Rizai.
Rizai, an Albanian national, was an associate of notorious fugitive and notorious criminal Vassilis Palaiocostas with whom he escaped from prison twice.