ATHENS, Greece >> Suspected domestic terrorists detonated a car bomb outside a Bank of Greece building in the heart of Athens Thursday, causing damage but no injuries in a brazen attack hours before a landmark bond issue by the financially struggling country.

No group claimed responsibility for the 6 a.m. (0300GMT) explosion, which shattered windows in the central bank branch and buildings up to 200 meters away, and left the charred remnants of a car with only two wheels still recognizable.

The attack hit a largely commercial zone with a large shopping mall and banks, a few blocks from the Greek parliament. It came one day ahead of a visit to Athens by German Chancellor Angela Merkel, whose country is the largest single contributor to Greece’s bailout program.

Police said two anonymous calls — to a news website and a newspaper — gave a 45-minute warning. Apart from a couple of security guards, nobody else was in the immediate area, which police swiftly cordoned off.

Forensic experts began combing through the blast site, while gaggles of office workers unable to get to work gathered in nearby cafes. 

An officer said the size and composition of the bomb were still unclear, and the anti-terrorism squad was taking over the case. He spoke on condition of anonymity as the investigation is still at a very early stage.

The news website that received one of the anonymous calls at 5:11 a.m. local time (0211 GMT) said the caller warned a bomb containing 75 kilograms (165 pounds) of explosives had been planted in a car.

The attack comes as Greece returns to borrowing on the international bond market. The country announced Wednesday it was issuing a five-year bond, its first since it became locked out of international markets in 2010.

The government has hailed the return to the bond market as proof that the country is emerging from its deep financial crisis.

“The evident target of the attackers is to change this image, and change the agenda,” government spokesman Simos Kedikoglou said on an early morning television news show. “We will not allow the attackers to achieve their aim.”

Since 2010, Greece has relied on funds from an international bailout, in return for which it has imposed deeply resented spending cuts, tax hikes and labor market reforms. Greece’s economy has shrunk by a quarter, while unemployment hovers at 28 percent.

Greece has a long history of domestic militant groups who plant usually small bombs late at night that rarely cause injuries. Although the country’s deadliest terrorist group, November 17, was eradicated and its members jailed in the early 2000s, several newer groups are still active.

One of the November 17 members vanished while on furlough from prison in January. Two suspected members of a different group, Revolutionary Struggle, vanished during their trial in 2012. That group is best known for firing a rocket into the U.S. Embassy in Athens and bombing the Athens Stock Exchange.