Several convicted members of Al-Qaeda’s affiliate in Yemen were among the more than two dozen prisoners who escaped from the Central Prison in Sanaa on Thursday night following an attack on the prison.

Armed militants exchanged fire with soldiers and set off two car bombs just after sunset to begin the attack on the prison. One blast opened a hole in the prison wall near a holding area for inmates convicted of terrorism offenses. By the time reinforcements arrived to control the assailants, 29 inmates had escaped, 19 of which had been convicted on terror charges, Yemen’s Interior Ministry said. The siege killed seven, McClatchy news service reported.

At least three escaped inmates were being held on charges associated with an assassination attempt on Yemen’s president, Abed Rabbo Mansour Hadi, early in 2013. Four escapees, including Hisham Mohamed Assem, were convicted and sentenced to death for a 2010 attack on an oil company in Sanaa. Another escapee facing a death sentence was Saleh Al Shawish, a skilled bomb maker who vowed to exact revenge at his 2010 sentencing.

“It’s a disaster,” a Yemeni official told McClatchy on the condition of anonymity. He said the escapees included “operational figures.”

No one has claimed responsibility for the attack, but Yemeni officials said it resembled tactics used by Yemen-based Al Qaeda in the Arabian Peninsula (AQAP), which has previously undertaken similar prison breakouts.

Analysts say the prison raids are, in part, effective for Al-Qaeda given it can often recruit more effectively inside prisons than it can on the outside. “Then, when a prison break occurs, all these new members rush to join al Qaida and the problem grows,” said Gregory Johnsen, an expert on AQAP in Yemen.

Many blame Yemeni Interior Minister Abdulqader Qahtan and other security officials for the security vacuum in the country, and for not increasing security at prisons housing AQAP members despite the organization’s frequent targeting of jails.

Others believe, based on the ease of the siege, that the perpetrators had inside help, echoing long-held beliefs that AQAP has effectively infiltrated Yemen’s security forces.

Yemen’s security troubles have exacerbated US concerns about releasing Yemenis held at Guantanamo Bay to their home nation. Yemenis represent the majority of the 155 detainees held at the US military prison.

US drone strikes in Yemen have become more frequent than those in Pakistan, formerly the most active theater for American drone activity. Britain’s Bureau of Investigative Journalism estimates that at least 273 civilians in Pakistan, Yemen and Somalia have been killed by drone strikes launched under President Barack Obama’s watch.