EL-ARISH, Egypt (CBSNewYork/AP) — Militants attacked a crowded mosque during Friday prayers in the Sinai Peninsula, killing at least 235 people in the deadliest ever attack on Egyptian civilians by Islamic extremists.

Officials said militants in four off-road vehicles bombed the Sufi mosque and then sprayed worshipers with gunfire. More than 100 others were also hurt.

Egyptian president Abdel-Fattah el-Sisi called the attack “criminal” and said it “will not go unpunished.” Egypt’s presidency has also declared a three-day mourning period, Egyptian state news agency MENA reported.

On Twitter, President Donald Trump also condemned the attack, calling it “horrible and cowardly.”

“Horrible and cowardly terrorist attack on innocent and defenseless worshipers in Egypt,” he said. “The world cannot tolerate terrorism, we must defeat them militarily and discredit the extremist ideology that forms the basis of their existence!”

In a second tweet, Trump said he will be calling the president of Egypt to “discuss the tragic terrorist attack”

“We have to get TOUGHER AND SMARTER than ever before, and we will,” he added. “Need the WALL, need the BAN! God bless the people of Egypt.”

Sufis are members of Islam’s mystical movement. No group has taken responsibility for the attack, but experts say a local ISIS affiliate considers Sufis heretics because of their interpretation of Islam.

(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)