Sofia (ABC NEWS) - Bulgarian Prime Minister Boiko Borisov today said the explosion on a bus full of Israeli tourists was likely carried out by a suicide bomber who had a fake Michigan driver's license.

The attack occurred Wednesday on a parking lot outside Burgas Airport in Bulgaria.

Borisov said officials have yet to determine whether the suspect's U.S. passport was fake as well, according to The Novinite Daily.

The suspected bomber was described as a Caucasian man with long hair and wearing sports attire.

The Bulgarian foreign minister said the man had been in the country for four to seven days and was about 35 years old, according to multiple Bulgarian media outlets.

"From what we could see on the CCTV video cameras, we think it's a person who was a suicide bomber," Bulgarian officials in Burgas told ABC News. "The investigation is still going on in close cooperation with the Israelis and Americans."

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 body after he boarded the bus.

Bulgarian police are checking fingerprints with all international databases and analyzing bombers' DNA to see whether they can find a match with the suspected suicide attacker.

Officials earlier lowered the death toll to seven, including the suspected bomber, after mistakenly reporting that someone had died overnight. Thirty-two people remain in hospital.