An explosion tore through a bus in the Red Sea resort town of Taba, killing three people and injuring 14 on Feb. 16.

The blast, which occurred near the Taba border crossing between Egypt and Israel, ripped through the bus, believed to be carrying mostly South Korean tourists who had visited the ancient monastery of St. Catherine’s in central Sinai, Egyptian officials said.

Ansar Beit al-Maqdis, an al-Qaida-inspired Islamist militant group based in Sinai, may have been responsible for the attack, although at times the military-backed Egyptian government has leveled the blame upon the Muslim Brotherhood. The Brotherhood has denied responsibility for any terrorist attacks.

No group has yet claimed responsibility for Sunday’s explosion, but if Ansar Beit al-Maqdis or another militant organization were involved, it would mark a clear shift from targeting police and security to hitting tourists.