Al-Qaeda-linked Islamist group Ansar Bayt al-Maqdis took responsibility for Sunday’s bus bombing in the Egyptian town of Taba that left 4 dead and 13 injured.

On its Twitter account, the organization promised to continue to attack Egypt’s economy, tourism, and military, Israel Radio reported.

The bomb tore through the bus carrying 31 South Korean tourists and their guide near an Egyptian border crossing with Israel in South Sinai on Sunday.

Three South Koreans — two men and a woman — were killed along with the Egyptian driver, the ministry confirmed.

The tourists were all members of the same church group from the central South Korean county of Jincheon who were on a 12-day trip through Turkey, Egypt and Israel.

It was the first attack on tourists since the ouster of Islamist president Mohamed Morsi by the army in July sparked civil unrest and a spate of attacks across Egypt that have mainly targeted security forces.

The bomb exploded in the front part of the bus at the Taba border crossing with Israel, Cairo’s interior ministry said.

The tourists had set off from Cairo and were waiting at the crossing to enter Israel when the explosion happened, it said.