Six people died and more than 30 were injured in a powerful blast on a tourist bus at Burgas Airport on the Bulgarian Black Sea coast on Wednesday afternoon, the Bulgarian Foreign Ministry said.

Photo taken on July 18, 2012 shows the wreckage of the bus (mark with a circle in the rear of the front bus) after a powerful blast at the Burgas Airport on the Bulgarian Black Sea coast, in which six people were killed and more than 30 others injured on Wednesday afternoon. All the passengers on board the bus were one Italian, one Slovak and one U.S. citizens, and the others were Israeli citizens. (Xinhua)

"Five people died at the scene and one died later in hospital, and 32 people were admitted to hospital, of which three are in intensive care," the ministry said in a statement on its website.

The tourists arrived in Bulgaria from Tel Aviv on an Air Viva charter flight No. 392 at 4:43 pm local time (1343 GMT). On board were 154 passengers, including 146 adults and eight children. Among the passengers were one Italian, one Slovak and one U.S. citizen. All the others are citizens of Israel, the ministry said.

"Bulgarian authorities are working on the theory that this was a terrorist attack. Burgas Airport has been closed temporarily," the ministry said.

"Bulgaria will do everything in its power to clarify the causes of this terrible incident," said Foreign Minister Nickolay Mladenov, who immediately went to the scene.

The minister expressed his condolences in a conversation with his Israeli counterpart Avigdor Lieberman and pledged to keep him informed of the details of the incident.

Bulgarian President Rosen Plevneliev and Interior Minister Tsvetan Tsvetanov also went to the scene, the ministry said.

Bulgarian officials are in constant contact with Israeli authorities and will provide information every hour to media on the scene, the ministry added.

Source: Xinhuanet