Militants have killed at least 235 people and wounded many more at a mosque in Egypt, after detonating a bomb and shooting fleeing worshippers and ambulances.
Attackers targeted members of Egypt's security forces as they were attending Friday prayers at the Al Rawdah mosque in Bir al-Abed, near Arish.
Egyptian President Abdul Fattah al-Sisi held emergency talks with security officials in the wake of the incident and declared three days of mourning, the BBC reports.
US President Donald Trump responded to the attack on Twitter. He wrote: "Horrible and cowardly terrorist attack on innocent and defenseless worshipers in Egypt. The world cannot tolerate terrorism, we must defeat them militarily and discredit the extremist ideology that forms the basis of their existence!"
Theresa May tweeted: "Appalled by the sickening attack on a mosque in North Sinai. Condolences with all those in #Egypt affected by this evil and cowardly act."
UK Foreign Secretary Boris Johnson said he was deeply saddened by the 'abhorrent attack'.
"My sincere condolences to all those affected by such a barbaric act," he tweeted.
The UK Ambassador to Egypt, John Casson, said that he was 'disgusted' by the 'evil attack that killed and injured so many Egyptians in Sinai today'.
He added: "These attacks on people praying in mosques & churches only strengthen our determination to stand together, & defeat terrorism & hate."
The attack comes following an escalation of insurgence in the region following mass anti-government protests in July 2013.
In July this year, 23 soldiers were killed when suicide car bombs hit two military checkpoints in the Sinai, an attack claimed by ISIS.