Kuwait City, Asharq Al-Awsat—Kuwait is investigating whether the perpetrator of last week’s deadly attack on a Shi’ite mosque had links to the “Peninsula Lions,” an Al-Qaeda-linked group that staged a series of attacks in the oil-rich country in 2005.

Speaking to Asharq Al-Awsat on the condition of anonymity, a Kuwaiti security source said there were reports that jailed Peninsula Lions members shouted “Allahu Akbar” (God is great) upon receiving the news of Friday’s deadly attack on the Imam Al-Sadiq Mosque in the neighborhood of Sawabir in Kuwait City.

The incident has prompted the authorities to investigate whether the perpetrator of the attack had any links to the Peninsula Lions group whose members have been killed, imprisoned or fled Kuwait.

Kuwait dismantled the group in 2005 and jailed 37 of its members on charge of belonging to Al-Qaeda.

Nine members were killed during clashes with Kuwaiti police in early 2005 and six were given death sentences.

Kuwait has identified the suicide bomber as Fahd Suleiman Abdul Mohsen Al-Qaba’a, a 23-year-old Saudi citizen who crossed into the neighboring country on the same day he carried out the attack.

It also arrested the man who drove the suicide bomber to the mosque and the owner of the house where he was staying in Kuwait.

The Islamic State of Iraq and Syria (ISIS) has claimed the attack that killed 27 people and injured 277.

In a statement on Sunday the Kuwaiti Interior Ministry said they had searched the driver’s home and found evidence showing he was a follower of “fundamentalist and deviant ideology.”

According to the source, the owner of the house has links to the Peninsula Lions and was previously sentenced to four years in prison for hiding information about the terrorist group.

Kuwaiti authorities believe that a cell of at least seven people is responsible for masterminding the attack, smuggling explosives into Kuwait and helping Qaba’a, the source said.