Authorities said all three were conscious and hospitalized in stable condition. "I unequivocally condemn the attack against Lucas Papademos," Greek Prime Minister Alexis Tsipras, who was attending a NATO summit in Brussels, tweeted from his official account. "I wish a speedy recovery to him and the people who accompanied him."
Police were on alert to determine whether any other parcel bombs might have been sent out, and were checking postal and courier services. There was no immediate claim of responsibility for the attack, but Greek politicians have been targeted in the past by militant far-left and anarchist groups.
A statement from the Greek Health Ministry said Papademos, 69, was being treated for wounds in his right thigh and upper body. He served as prime minister for six months in 2011-2012 and is also a former deputy governor of the European Central Bank.
"We are saddened by the attack against our former colleague, Lucas Papademos, a brave public servant of Greece and Europe," European Central Bank President Mario Draghi said in a statement. A police official said the explosion occurred when Papademos opened an envelope inside the car. Anti-terrorism police were at the hospital where Papademos was being treated in order to interview him on the details of the envelope.
A second police official said one of the other two wounded in the blast told anti-terrorism police that he had handed Papademos the mail earlier, and that before doing so he had put it through an X-ray machine and nothing suspicious showed up.
Both officials spoke on condition of anonymity pending official announcements. The government described the blast as a terrorist attack. "It is obvious and self-evident that the Greek government unreservedly and categorically condemns the attack against the former prime minister, Mr. Papademos," said government spokesman Dimitris Tzanakopoulos.
Earlier this year, a group called Conspiracy Cells of Fire, claimed responsibility for sending parcel bombs to the German Finance Ministry and the Paris office of the International Monetary Fund, where a small explosion injured one person.
The group had also claimed responsibility for a spate of parcel bombings in 2010 targeting several embassies in Athens and the offices of European leaders abroad. Most of the devices were intercepted or destroyed by police, but one device injured a parcel company employee in Greece.
In the same year, a parcel bomb disguised as a gift exploded at the office of the Public Order Minister in Athens, killing one of the minister's top aides. In Thursday's attack, police said Papademos' police escort had been in a car behind the former prime minister's vehicle, and that the other two people wounded were Bank of Greece employees.
Authorities cordoned off the area, and forensics experts were investigating the scene for evidence. The former prime minister's car was parked by the side of the road, in front of its escort vehicle. Papademos' car bore little sign of damage, except for buckling on two doors.
The explosion damaged the car's windshield, leaving no other sign of damage, but startled bystanders. "I heard a loud bang, thought at first it was a car crash or a burst tire," said Stelios Tavlaridis, who keeps a shop a dozen meters from the blast site.
"The police were there almost instantly, in no time. It was really impressive. I've never seen anything like it," Tavlaridis said. Conservative opposition leader Kyriakos Mitsotakis, whose brother-in-law, conservative politician Pavlos Bakoyannis, was shot dead in 1989 by members of far-left terror group November 17, expressed "rage and pain" at the attack against Papademos.
"At some point we realize in this country that dealing with terrorism must take the highest priority. Terrorists are enemies of democracy," he said. A respected economist, Papademos headed a provisional coalition government credited with preventing the collapse of the country's international bailout at the time. He also served as governor of the Bank of Greece between 1994 and 2002, when the country adopted the euro currency.
Derek Gatopoulos, Raphael Kominis, and Yorgos Karahalis contributed to this report. Follow Becatoros at http://www.twitter.com/ElenaBec