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) ||||| Assailants attacked the offices of Microsoft in Athens early Wednesday, driving a van through the front doors and setting off an incendiary device that burned the building entrance, police said. 
 
 A security guard walks near a destroyed van outside the entrance of Microsoft's offices in northern Athens, Wednesday, June 27, 2012. Assailants attacked the offices of Microsoft early Wednesday, driving... (Associated Press) 
 
 A security guard walks outside Microsoft's offices in northern Athens, Wednesday, June 27, 2012. Assailants attacked the offices of Microsoft early Wednesday, driving a van through the front doors and... (Associated Press) 
 
 A police officer investigates a destroyed van outside the entrance of Microsoft office in northern Athens, Wednesday, June 27, 2012. Assailants attacked the offices of Microsoft in Athens early Wednesday,... (Associated Press) 
 
 A policeman stands in front of Microsoft's offices in northern Athens, Wednesday, June 27, 2012. Assailants attacked the offices of Microsoft early Wednesday, driving a van through the front doors and... (Associated Press) 
 
 There were no reports of injuries in the pre-dawn attack on the U.S. company's headquarters in the Greek capital, located in the Maroussi suburb north of the city center. 
 
 There was no immediate claim of responsibility. Authorities said no warning call had been made before the attack. 
 
 Greece has experienced attacks by several small armed anarchist or domestic terrorist groups for decades, which usually target official buildings, banks or symbols of state power with small bombs or incendiary devices. The attacks usually occur late at night and rarely cause injuries. 
 
 Police said initial information indicated three people had been inside the van. They forced the two security guards at the building to leave before they reversed the van into the front entrance, smashing the door. 
 
 The two security guards were giving testimony to police. 
 
 The assailants then triggered an incendiary device inside the van that police said appeared to have consisted of camping gas canisters and several containers of gasoline. 
 
 Police forensic teams examined the burned-out van, which was still outside the blackened entrance later Monday morning. 
 
 Although they have died down over the past year, attacks had spiked following the fatal police shooting of a teenager in Athens in December 2008 that led to widespread riots across the country. 
 
 One group that had appeared in the aftermath of the rioting had set itself apart by claiming responsibility for shooting dead an anti-terrorism police officer in central Athens in 2009 and a journalist in 2010.
– 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.