The mother of a politician from Greece’s ruling New Democracy party has died of injuries sustained in one of a series of suspected arson attacks targeting party officials.

Vagia Nestora, 72, suffered extensive burns and multiple organ failure, according to the hospital where she was taken in the northern city of Thessaloniki.

She was wounded in an explosion and fire at the apartment building where her daughter, Afroditi Nestora, lives.

Three separate attacks involving petrol bombs and other improvised devices took place within minutes of each other in Thessaloniki in the early hours of Wednesday.

Prime Minister Kyriakos Mitsotakis travelled to the hospital in Thessaloniki following the attacks and told reporters that “violence has no place in an organised society”. He vowed that those responsible would be found and brought to justice.

Speaking before Vagia Nestora’s death, he vowed that those who had carried out such attacks under the guise of social struggle were “nothing more than criminals, they will be treated as such”.

Hospital officials said Vagia Nestora had been admitted in a critical condition with burns covering about 80% of her body and she died later despite receiving intensive care treatment.

Her daughter, a party candidate, also suffered burns and smoke inhalation and remains in hospital. Afroditi Nestora’s father, who has underlying health problems, and two other residents were also admitted after suffering breathing difficulties.

Police said improvised incendiary devices had been placed outside the apartment building, triggering the explosion and fire. The blast destroyed two cars, damaged several motorcycles and caused extensive damage to the building.

The two other attacks targeted the homes of Zisis Ioakeimovits, chairman of New Democracy’s Thessaloniki administrative committee, and former New Democracy MP Savvas Anastasiadis. No injuries were reported in those incidents.

Reports suggested the three attacks took place at 04:18, 04:23 and and 04:35 on Wednesday

Greece’s Counter-Terrorism Service has taken over the investigation and is examining whether the three attacks were coordinated. Officers are analysing CCTV footage and have not announced any arrests.

No group has claimed responsibility for the attacks.