The Egyptian military launched airstrikes on militant hideouts overnight Friday, in response to the horrific mosque attack earlier that day, the deadliest in the country's modern history.

Egyptian President Abdel-Fattah el-Sissi had promised to respond with "brute force" in retaliation for the attack on a village mosque that officials say killed 305 people and wounded more than 128.

The army didn't give details on the number of airstrikes or targets, according to The Associated Press.

A clearer picture was also emerging Saturday of the bloody attack in the country's North Sinai region.

"The public prosecutor's office says 25 to 30 bearded gunmen dressed in black started shooting through the door and windows of a mosque in the tiny village of al-Rawda," NPR's Jane Arraf told our Newscast unit. "It was during Friday prayers at the start of the sermon."

Other gunmen in vehicles started shooting as worshippers started to flee, and the attackers also launched grenades into the mosque. At least 27 of the people killed were children.

"When the shooting began everyone was running, and everyone was bumping into one another," Magdy Rezk, a wounded survivor, told Reuters from his hospital bed. "But I was able to make out masked men wearing military clothing."

It was still unclear Saturday morning who was responsible for the attack, as no group had yet claimed responsibility. The Egyptian government has been battling an Islamic State affiliate in the region for years, however, and the prosecutor's office said one of the attackers was waving a flag that bore a phrase consistent with ISIS messaging.

Many of the victims of Friday's attack were Sufi Muslim, an aspect of Islam that reveres saints and uses music and dance to worship. ISIS and its affiliates consider the school of practice, often known as Islamic mysticism, to be heresy.

Sufi shrines have been the targets of extremist attackers in Pakistan in recent years, but an attack on a mosque would represent a shift for militants in the Egyptian region. Sinai militants have previously attacked troops and police as well as places of Christian worship.

They did, however, behead an elderly Sufi man last year after accusing him of witchcraft.

Imams in the al-Rawda village where the attack happened told NPR that mosques in the area had been warned by militants over the past month not to conduct religious ceremonies.

Sissi called for three days of national mourning after the attack, as well as the building of a memorial mausoleum. The main gateway for Palestinians out of the Gaza Strip was closed after the attack.

Officials from around the world, including Israel, Iraq, France and the United Kingdom, publicly condemned the attack, as NPR's Nicole Hernandez and Rebecca Feldhaus Adams reported.

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