A makeshift time-bomb lightly injured two security staff at a large shopping center near Athens on Sunday, in escalating political violence in the crisis-hit country.
The blast followed gun and bomb attacks on political figures and journalists in recent weeks, some claimed by anti-establishment leftists angry about Greece's financial woes.
The device, which exploded shortly before 11 a.m. (4.00 a.m. ET), was left in a rubbish bin close to a National Bank branch at The Mall shopping center in the middle-class Maroussi area, said police. There have been no claims of responsibility so far.
The time bomb contained about 1.5 kilos (3.3 lb) of gelatinous dynamite and a mixture of ammonium nitrate and fuel oil, known as ANFO, according to a police official who declined to be named.
While shops are closed on Sunday, cafes, cinemas and restaurants in the center were open for business. Police evacuated the mall after two warning calls to a newspaper and a news site, made about half an hour earlier.
Maroussi mayor George Patoulis told state Net TV about 200 people were in the shopping center.
"We were doing inventory in our shop and the police told us to evacuate. We ran out and in 10 minutes we heard the blast. It all happened really fast," a shop clerk told SKAI radio.
Police shut down a metro station, combed the center for other bombs and checked security cameras. Authorities said the two security guards suffered minor cuts from shattered glass.
A camera showed two persons, probably male, placing a bag in the rubbish bin about half an hour before the warning call to the newspaper and then leaving the site, police said.
All major political parties condemned the attack, the first to cause injuries in several years.
"We are dealing with a new type of terrorism that not only picks symbolic targets but wants blood and death," the co-ruling Socialist PASOK party said in a statement.
The country's public order ministry urged the political class to work together to end the violence.
"It is not enough to verbally condemn the incident, there must be an absolute isolation of violence and terrorism by the political system. The message is our democracy cannot be terrorized," it said in a statement.
The government has said in the past Syriza, the radical leftist main opposition party, tacitly backs anti-establishment groups. Syriza, which condemned Sunday's attack, denies this.
"The attack shocked us. It is the first time commercial areas are targeted. This scares consumers and hurts the market at a time when social peace is needed," the president of the Confederation of Greek Commerce, Vassilis Korkidis, told Reuters.
Greece is in the sixth year of a recession that has fuelled anger against banks, foreign lenders and politicians, blamed by Greeks for bringing the country close to bankruptcy.
The U.N. refugee agency, UNHCR, says racist attacks have also risen to alarming levels in Greece during the crisis, and hundreds of demonstrators in Athens on Saturday paraded the coffin of a Pakistani immigrant who was stabbed to death.
On Monday, unidentified attackers opened fire on the Athens headquarters of Greece's co-ruling New Democracy party with a Kalashnikov assault rifle.