An explosion shredded a bus carrying Israeli tourists outside an airport in Bulgaria. At least four people were killed and dozens injured.

Police say several others buses were also damaged.

Israeli Defense Minister Ehud Barak blamed Tehran for the blast and said Israel would respond.

The explosion comes on the 18th anniversary of a 1994 bomb attack on the headquarters of Argentina's main Jewish organization -- which killed 85 people.

Deborah Gembara, Reuters.