Police were yesterday probing an armed attack on the Athens headquarters of conservative New Democracy, which leads the coalition government, after unidentified gunmen fired shots at the office of ND leader and Prime Minister Antonis Samaras, triggering fears of a resurgence of action by leftist guerrilla groups.

The predawn attack, which caused no injuries as the offices on Syngrou Avenue had been empty at the time, was carried out by at least three assailants, one wielding a Kalashnikov assault rifle, the other a .357 Magnum revolver and a third driving the getaway car, according to police. A bullet from a Kalashnikov pierced the window of Samaras’s third-floor office while a bullet from a Magnum was found on the roof, according to police. Nine Kalashnikov casings were discovered outside the party’s offices, police said. The getaway car, a vehicle reported stolen two days earlier, was found in the coastal suburb of Palaio Faliro later Monday.

The attack followed a spate of gas canister bombings targeting political party offices and prominent journalists over the past few days and the firebombing of the Athens home of government spokesman Simos Kedikoglou’s brother on Saturday night.

Kedikolgou condemned the new wave of violence, referring to a “dangerous escalation of terror.”

Samaras is to meet Tuesday with his coalition partners, PASOK chief Evangelos Venizelos and Democratic Left leader Fotis Kouvelis, to discuss the spike in violence which appears to have been at least partly triggered by a recent police crackdown on squats in the capital.

Commenting on Monday’s attack, Samaras told reporters that the government would not tolerate violence. “You can shoot a person, like the building that they shot,” he told reporters Monday evening outside ND’s offices. “You cannot shoot democracy though. Let this be heard by those who need to hear it: Democracy will not be terrorized.”

The assault was roundly condemned by all political parties. In a statement, socialist PASOK called on all parties and Greek society to unite behind the condemnation of all forms of violence.

SYRIZA leader Alexis Tsipras called Samaras from Berlin, where the leftist leader met with German Finance Minister Wolfgang Schaeuble, to express his sympathy and ask for a full investigation into the attack.

But SYRIZA lawmakers clashed with coalition MPs on the issue. Party

spokesman Panos Skourletis accused the government of dangerous polarization and said the attack was distracting from the pressing issues facing Greece. His SYRIZA colleague and WWII hero, Manolis Glezos, angered coalition MPs by questioning whether “parastate” forces close to New Democracy were behind the raid. His words prompted New Democracy deputy Makis Voridis to remark that all those convicted or held on suspicion of terrorist acts in Greece were anarchists or members of the extreme left.

Anti-terrorism officers are reportedly re-examining their files on Revolutionary Struggle and Conspiracy of the Cells of Fire, two leftist guerrilla groups that were broken up in 2010 and 2011 respectively. They are also examining the possibility that a new group was behind Monday’s attack.

Police were also investigating a series of arson attacks on bank ATMs in Athens and the western port of Patra that caused damage but no injuries. Unidentified assailants doused cash machines in Neo Iraklio, north of Athens, and Drapetsona, near Piraeus, in gosoline before setting the fuel alight. Three similar arson attacks on ATMs in Patra occurred in close succession.

There was no claim of responsibility for the attacks in either city, and police gave no indication of where their suspicions lay, but the style is reminiscent of tactics used by members of anti-establishment and anarchist groups.