Dutch police said on Thursday evening they believe they have foiled a major terrorist attack in the Netherlands with the arrest of seven men in Arnhem and Weert.

The men range in age from 21 to 34 and three of them, including the ringleader, have previous convictions for attempting to join IS in Syria, the public prosecution department said.

The department began an investigation into the 34-year-old man they suspect to have led the cell in April, following a tip-off from the AIVD security service. The AIVD said the man, an Iraqi national, had been planning an attack at a major event in the Netherlands with the aim of creating as many victims as possible.

‘The plan may have involved jackets packed with explosives and Kalashnikovs at an event and a car bomb elsewhere. The investigation into the exact target is still ongoing,’ the public prosecution department said.

‘The suspects were looking for AK47s, hand guns, hand grenades, suicide jackets and the ingredients for a car bomb,’ the department said. ‘They had also been looking for training in the use of guns and the suicide jackets.’

The investigation picked up quickly this month because the suspects’ preparations were becoming more advanced, the department said.

The public prosecution department says it is convinced that a terrorist attack has been averted due to the arrests. The threat level in the Netherlands remains ‘substantial’, one below the maximum risk level.

The seven men, who are being held in isolation and only have contact with their lawyer, will appear in court on Friday for a remand hearing.