An explosion ripped through a tourist bus near Egypt's border with Israel killing three South Korean tourists and their Egyptian driver.
The bus, carrying 33 tourists, was travelling from St. Catherine's Monastery, in central Sinai, to Israel, when it exploded at the border crossing in Taba.
The South Korean foreign ministry confirmed the death of two of its nationals and say the tourists were members of a Christian church group.
At least 12 people were seriously wounded.
Security officials say the cause of the bombing was not clear, but that it most likely was from a bomb in or near the vehicle.
Islamist militants, based in the Sinai peninsula, have increased attacks on security forces since the overthrow of former president Mohamed Morsi in July.