A riot policeman runs from angry protesters Wednesday in the northern Greek port city of Thessaloniki. Deadly riots over harsh new austerity measures engulfed the streets of Athens on Wednesday, and three people were killed as angry protesters tried to storm parliament, hurled Molotov cocktails at police and torched buildings.

Athens, Greece ? Rioting over harsh austerity measures left three people dead in a torched Athens bank and clouds of tear gas drifting past parliament, in an outburst of anger that underlined the long and difficult struggle Greece faces to stick with cutbacks that come with an international bailout.

The deaths were the first during a protest in Greece in nearly 20 years.

Fear that the bailout won’t stop the debt crisis from spreading to other financially troubled EU countries like Portugal and Spain intensified amid the violence Wednesday, as credit ratings agency Moody’s put Portugal on watch for a possible downgrade. The euro sank, dipping below $1.29 for the first time in over a year.

Greece faces a May 19 due date on debt it says it can’t repay without help. The new government cutbacks, which slash salaries and pensions for civil servants and hike consumer taxes, are being imposed as a condition of getting a $142.16 billion package of rescue loans from the International Monetary Fund and the other 15 European Union countries that use the euro as their currency.

Many Greeks realize cutbacks are necessary to pull their country, with a debt of $387.72 billion, back from the brink of default, and reaction until now had been relatively muted by Greece’s standards. But with people beginning to feel the pain of austerity measures, anger boiled over.

Although violent demonstrations are commonplace in Greece, they often occur as set-piece clashes between anarchist youths and police and rarely lead to serious injuries. The deaths shocked public opinion and could affect future demonstrations.

An estimated 100,000 people took to the streets during a nationwide general strike that grounded flights, shut all services and pulled news broadcasts off the air.

Hundreds of demonstrators — including far right wing supporters — broke away from the marches and tried to storm parliament, shouting “thieves, traitors.” At the opposite end of the political spectrum, groups of anarchists hurled Molotov cocktails and ripped-up paving stones at buildings and police, who responded with barrages of tear gas.

Three bank workers — a man and two women all between 32 and 36 — died of smoke inhalation after demonstrators torched their bank, trapping them. Four others were rescued from a balcony.

A senior fire department official said demonstrators prevented firefighters from reaching the burning building. “If we had intervened earlier, the loss of life could have been prevented,” the official said on condition of anonymity pending an official announcement.

Fifteen civilians and 29 police were injured in what Civil Protection Minister Michalis Chrisohoides called “a black day for democracy.” Twelve people were arrested in Athens and another two in the northern city of Thessaloniki, which also saw clashes between police and demonstrators.

In Brussels, EU officials desperately tried to calm market fears that Greece’s debt crisis was spreading, insisting it was a “unique case” combining profligacy and tampered accounts. EU President Herman Van Rompuy insisted the growing debt problems in Spain and Portugal had “absolutely nothing to do with the situation in Greece.”

The shocks from Greece have shaken world markets and raised questions about whether the rally in stocks can continue.