At least four people, including three Koreans, have been killed and more than 20 injured after an explosion ripped through a tourist bus near a border crossing between Egypt and Israel on Sunday.
None of the injured are said to be in critical condition.
Egypt's interior ministry did not state the cause of the blast, but two security sources said a bomb planted either inside or near the bus was used.
The bus was carrying 33 people -- 31 Korean nationals from a church in Jincheon, Chungcheongbuk-do Province, their Korean guide, and an Egyptian bus driver.
Egyptian authorities say the group was on its way to Israel after visiting Saint Catherine's Monastery -- a popular tourist attraction in South Sinai.
The group was reportedly on a 12-day pilgrimage that included stops to Turkey, Egypt and Israel.
Korea's foreign ministry has confirmed three Koreans and the Egyptian bus driver were killed in the attack.
Army sources say it was a terrorist attack, but no group has stepped forward to take responsibility.
Militants in Sinai have stepped up their attacks against police and army forces in recent months, after the army ousted President Mohammed Morsi last July.
The Egyptian government says it's very disappointed by the attack, and hoped it was an isolated incident that would not be repeated.
Korea's foreign ministry says it has dispatched three of its officials in Egypt and Israel to the bombing site.
Kim Min-ji, Arirang News.