An ISIS statement posted on social media earlier on Saturday identified the bomber as Abu Suleiman al-Muwahed and said the target was a “temple of the rejectionists” – a term used by the Islamist militant group to refer to Shiite Muslims – and said dozens were killed or wounded.

The bomb was reportedly detonated as worshippers kneeled on the ground halfway through the weekly Friday prayers at the Imam Sadiq Mosque, according to Al Arabiya.

The GCC Secretary General Abdullatif bin Rashid al-Zayani said the Kuwait attack was a “horrifying crime” and against “Islamic values.”

Kuwaiti Prime Minister Sheikh Jaber al-Mubarak al-Sabah said on Friday that a suicide bombing at a Shiite Muslim mosque in the

Friday’s attack is the first such bombing targeting Kuwaiti Shiites, who make up around one-third of the country’s native population of 1.3 million people.

“This incident targets our internal front, our national unity,” Sheikh Jaber told Reuters after visiting the wounded at the Emiri hospital. “But this is too difficult for them and we are much stronger than that.”

Soon after the blast, Kuwait’s Emir Sabah al-Ahmad al-Jaber Al-Sabah visited the scene.

A witness said the bombing happened when the mosque was packed with some 2,000 worshippers during Friday prayers.

“It is a suicide bombing,” a security official told AFP.

Friday midday prayers are typically the most crowded of the week, and attendance increases during the holy Muslim month of Ramadan, which started last week.