Berlin's Greens justice minister Dirk Behrendt faced calls to quit Thursday from the city-state's opposition Christian Democrats after an escape fit for a movie script.
It remained initially unclear whether the escapees had accomplices or which tools they had used.
They had reported for duty at the prison workshop as normal earlier in the day, authorities said.
Behrendt was due to give a late-afternoon press conference.
German media said bent concrete reinforcing metal projected from the escape route forced near ventilation slots. Broken concrete pieces were also visible at the facility.
The prison, located north-west of the city center, houses 362 inmates, according to official data.
On its fringe is the Plötzensee memorial, where during World War Two Adolf Hitler's terror regime executed some 3,000 persons, including those involved in the failed bid to assassinate him on July 20, 1944.
ipj/jil (dpa, AP)Hole-in-wallescapefromBerlinprison