Iraq’s Interior Ministry said Friday the jailbreak of 102 prisoners, including 47 Al-Qaeda-linked inmates, was an inside job.

Twenty people, including 16 inmates and four guards, were killed in the late Thursday night break at Tasfirat prison in Saddam Hussein’s hometown of Tikrit, 80 miles north of Baghdad. Authorities on Saturday enforced a curfew in order to track the escaped fugitives, which represented one-third of the prison’s 303 inmates. Twenty-three have been recaptured.

According to the BBC, armed militants set off the break by attacking the prison, including a suicide bomber who detonated a car bomb outside the gates. Gunmen then stormed in.

In a statement, the ministry said there was “clear collusion” between some guards and inmates: Weapons were brought into the prison during family visits, and wardens left locks inside the facility open.

“The cells were not searched for a long period, which indicates more deliberate negligence that led to this incident,” the statement said.

After taking control of a large portion of the prison, escapees used other inmates as human shields in order to make their way out, it said.

According to the BBC, Iraqi lawmaker Hakim al-Zamily said escapees took documents identifying the individuals who had turned them in, and also destroyed personal files on inmates, making it “impossible” to track them down.

The Associated Press contributed to this report.