At least 235 people were killed and 109 others injured in a gory terror attack on a mosque in Egypt’s northern Sinai region on Friday, reported state media, making it one of the deadliest attacks on civilians in the country.

The attack on Al-Rawdah mosque, affiliated with Sufi groups, took place during Friday prayers.

The assailants planted home-made explosive in the mosque in the town of Bir al-Abd, near Arish, and detonated them as worshipers were leaving after prayers. They also shot at anyone who tried to escape, a security official told Efe news.

The gunmen also fired at ambulances transferring the injured to hospital, eyewitnesses said.

Pictures from the scene showed rows of bloodied victims inside the mosque. The blasts from improvised explosive devices caused considerable damage to the mosque, said state-run Al Ahram Online.

Speaking to state-run Masriya TV, Egyptian Health Ministry spokesman Khalid Mujahid described the incident as a “terrorist attack”.

One report said the target appeared to be supporters of the security forces who were praying at the mosque. Egyptian President Abdel Fatah el-Sisi was meeting with a security committee to discuss the bloodbath.

Egypt declared three days of national mourning. No group has claimed responsibility for the massacre.

In a statement, El-Sisi said that Egyptians will “derive hope and determination from such pain to triumph in the war against black terrorism”.

The statement offered condolences to the families of the victims, stressing that the “vile and treacherous” activity will not pass without a decisive punishment and that the perpetrators will be brought to justice, said Al Ahram Online.

The President also ordered compensation of EGP 200,000 and EGP 50,000 to the families of the dead and injured, respectively.

US President Donald Trump condemned the attack as “horrible and cowardly”. “The world cannot tolerate terrorism, we must defeat them militarily and discredit the extremist ideology that forms the basis of their existence!” he tweeted.

Egypt’s security forces have been fighting an Islamist insurgency based in the northern part of the Sinai Peninsula which has gained pace since the 2013 ouster of Islamist president Mohamed Morsi.

The insurgency has mostly targeted security forces, with attacks on military and police checkpoints common place.