A prison holding Taliban militants and extremist group members came under attack by gunmen in northwest Pakistan Monday night, enabling around 250 prisoners to escape.
Escapees from Dera Ismail Khan jail included top militants and inmates on death row, local officials told Reuters.
At least 12 people were killed in the overnight assault, the news agency reported, including five police officers and four prisoners whose throats were cut.
Security forces and militants wearing police uniforms battled into the early hours of Tuesday for control of the prison, which had housed around 5,000 inmates including 250 Taliban and other Islamist militants.
The attack on the jail started with several explosions at around noon local time. Grenades, rockets and seven suicide bombers were allegedly used.
A local resident described the initial blast as so loud that "it rattled every house in the neighborhood."
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Officials said the attackers were chanting "God is great" and "Long live the Taliban."
Pakistani Taliban spokesman Shahidullah Shahid claimed responsibility for the attack, saying that about 300 prisoners had been freed — a number disputed by later reports.
"The Taliban have loudspeakers and they are calling the names of their friends," said the town's civil commissioner, Mushtaq Jadoon.
Khalid Abbas, head of the provincial prison department, said authorities had received a letter threatening an attack. Prison authorities had even met to discuss security measures just hours before the raid, according to Reuters.
Unnamed officials told Reuters that they suspected the attackers may have had inside help — or at least, that prison guards had neglected their duties.
One senior government source called the incident as "a debacle of the highest order," according to the New York Times.
The city of Dera Ismail Khan has been placed under curfew and roads closed as police attempt to stop escapees fleeing into Pakistan's neighboring tribal regions, the Times reported. By Tuesday, officials claimed to have recaptured six prisoners.