1 of 4. A police investigator searches for evidence following an attack on Microsoft's Greek headquarters at Marousi suburb, north of Athens June 27, 2012. Gunmen rammed a van packed with gas canisters into Microsoft's Greek headquarters in Athens and then set the vehicle on fire, causing damage but no injuries, police said on Wednesday. 
 
 ATHENS (Reuters) - Gunmen rammed a van packed with gas canisters into Microsoft's (MSFT.O) Greek headquarters in Athens and then set the vehicle on fire, causing damage but no injuries, police said on Wednesday. 
 
 At least two people wielding pistols and a machine gun kept security guards away as they carried out the attack at about 0145 GMT, police said. 
 
 Arson attacks against banks, foreign firms and local politicians have become more frequent in Greece in recent years as the country battles soaring unemployment and struggles through a recession deepened by austerity policies imposed by foreign lenders. 
 
 Previous assaults have been mostly blamed on left-wing extremist groups, but police said it was too early to say who was behind Wednesday's attack. 
 
 The van, which contained three inflammable gas canisters and five cans of gasoline, was completely destroyed while the ground floor of the U.S. software firm's office suffered heavy damage, police said. 
 
 Microsoft said it would shut its office in the city while it assessed the damage. 
 
 "Staff were told not to come to work today, and probably also tomorrow," the company's spokeswoman Lia Komninou said on Skai TV. 
 
 The fire brigade estimated the damage at about 60,000 euros ($75,000). 
 
 In February, a small bomb was left on an empty subway train in Athens, which a far-left group fighting the austerity policies later claimed responsibility for. 
 
 Growing public anger at the impact of the austerity measures was reflected in two parliamentary elections in May and June, in which parties opposed to the terms of the country's international bailout performed strongly. 
 
 ($1 = 0.8019 euros) 
 
 (Reporting by Harry Papachristou; Editing by John Stonestreet) ||||| 1 of 3. Forensic experts search for evidence on a street where a car bomb went off in Athens April 10, 2014. 
 
 ATHENS (Reuters) - A car bomb exploded outside a central bank building in Athens early on Thursday, smashing windows but causing no injuries, just hours before Greece was due to make its first foray into the international bond markets in four years. 
 
 The dawn blast, which police believe was carried out by leftist or anarchist guerrilla groups, also came a day before a planned visit to Athens by German Chancellor Angela Merkel. 
 
 An anonymous caller warned a newspaper about 45 minutes before the explosion just before 6 a.m. (0300 GMT), saying it contained about 70 kg (155 pounds) of explosives, a police official said on condition of anonymity. A news website also received a warning call. 
 
 Witnesses saw debris strewn across the street in one of the busiest parts of central Athens that is lined with banks, shops and a mall. A second police official, who also declined to be named, said the force had yet to determine the amount and type of explosives used in the attack. 
 
 "It is clear that the attackers are trying to set the agenda," Government Spokesman Simos Kedikoglou told Skai TV. "We will not allow the terrorists to succeed." 
 
 Makeshift bomb and arson attacks have escalated since Greece adopted unpopular austerity measures in exchange for multi-billion euro bailouts by the European Union and International Monetary Fund from 2010. 
 
 Athens, which is seeking to send a strong political and economic signal that it is finally exiting its debt crisis, is expected to tap bond markets later on Thursday. 
 
 But public anger remains high after six years of recession that has sent unemployment to record highs of nearly 28 percent, eroded living standards and shut down thousands of businesses. 
 
 Greeks have had their incomes slashed by almost a third since 2010 and strikes against austerity are frequent. 
 
 Attacks against banks, government buildings, politicians, journalists and businesspeople are fairly common in Greece, which has a long history of political violence. 
 
 In 2009, a powerful car bomb exploded at the Athens stock exchange, slightly injuring one person and damaging the building One of Greece's most militant guerrilla groups, Revolutionary Struggle, claimed responsibility for that attack. 
 
 (Additional reporting by Harry Papachristou and Alkis Konstantinidis; Editing by Gareth Jones)
– If idle hands are the devil's hands, Greece is finding out the hard way: Gunmen this morning stormed Microsoft's Athens headquarters, ramming the building with a gasoline-laden van before setting fire to it. The attack injured no one, but heavily damaged the building's first floor and shut the office for at least the day, in what Reuters notes is the latest in a series of arson hits on banks and foreign companies as anger simmers over high unemployment and austerity measures in the financially strapped nation. No one has claimed responsibility for the Microsoft attack, but the AP notes that anarchist or radical left-wing groups are usually responsible.