Three attackers drove a van through the front of Microsoft's offices just north of Athens on Wednesday, marched out security guards at gunpoint, and tried to burn the building to the ground.

It's unclear who is behind the attack, but it's a worrying sign for foreign multinational corporations, coming as Greece struggles under the weight of a collapsing economy.

The attack happened during the very early hours of Wednesday morning, before staffers had shown up for work. The assailants "drove a van through the entrance to the building, ushered the two security personnel out of the building and then set the van on fire," a Microsoft spokesman said Wednesday.

No one was injured in the attack, which occurred in Maroussi, a suburb of Athens.

The blaze was put out, but the fire department estimates damages at about €60,000 ($75,000), according to local reports.

Microsoft Greece general manager Ernst-Jan Stigter said he learned of the attack at 4:30am. "They smashed the entrance, pulled out gasoline," he told Reuters in a – video interview. "They put it all over the place in an effort to burn the whole place down."

The attackers had pistols and an automatic rifle, according to Reuters.

Greece has been teetering on the brink of economic collapse for months, as the country and the European community struggle to stave off a default on its massive loans. After four years of recession, the country is broke, and the International Monetary Fund and the European Union have been demanding unpopular spending cuts from an increasingly unhappy populace.

Police are investigating the incident, Microsoft said.

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