A suicide bomber was responsible for the Wednesday terror attack targeting Israeli tourists at the Burgas Airport in which seven people were killed, Bulgarian Prime Minister Boyko Borisov said Thursday. The suspected bomber was carrying a US passport believed to be fake, according to the Sofia News Agency.Initial reports suggested that the explosion was caused by a bomb placed in the luggage compartment of the bus. However, an investigation carried out by Bulgarian authorities in conjunction with the FBI, CIA and Israeli authorities now points to a suicide bomber described as a Cauacasian man with long hair and sports attire, according to the report. Bulgarian Interior Minister Tsvetan Tsvetanov told a press conference in Burgas that the suicide bomber looked like a regular tourist. Tsvetanov said that the bomber had been in Bulgaria for between 4-6 days and that he was about 36 years old.The man was filmed walking around the airport for an hour prior to the attack by security cameras on the premises, according to the report. His body sustained the most damage in the blast, leading investigators to believe that he set off a bomb located on his person when he boarded the bus.An FBI check of the document's found on the man's body, including a passport identifying him as a Michigan resident, determined that they were counterfeit, according to the report.US President Barack Obama strongly condemned the "barbaric" attack on Wednesday, offering to aid in the investigation "and bring to justice the perpetrators of this attack." Obama phoned Prime Minister Binyamin Netanyahu after the attack offering his condolences. The two leaders agreed that the US and Israel would work together to investigate the attack.Netanyahu on Wednesday said Iran is likely behind the attack, vowing a powerful Israeli response."All the signs lead to Iran. Only in the past few months we have seen Iranian attempts to attack Israelis in Thailand, India, Georgia, Kenya, Cyprus and other places," Netanyahu said in a statement."This is an Iranian terror campaign that is spreading throughout the world," Netanyahu said. "Israel will react powerfully against Iranian terror."Yaakov Katz contributed to this report.