Six people have been killed after a gunman, using unregistered firearms, opened fire at a nursing home in northwestern Croatia on Monday. The gunman's mother was reportedly one of the victims shot dead, and five additional people were injured, according to a government minister.

The minister for labour, pension and family social policy, Marin Piletic, told reporters that one of the victims was a nursing home employee, per Reuters. "According to the information we have the mother of the killer had been in the nursing home for 10 years," she said.

CBS News reports that most of the victims were in their 90s.

Authorities have not yet given a motive for the attack but local news outlets reported that the gunman was a war veteran who was born in 1973. He reportedly fled the scene but was later arrested by police in a cafe down the street from the nursing home in the town of Daruvar.

"We are shocked," Prime Minister Andrej Plenkovic stated to reporters. "This is really a monstrous act of the murder of a group of people, of the mother and other very old people who happened to be there... We condemn this crime."

Croatia's president Zoran Milanovic took the incident as an opportunity to call for stricter gun laws, albeit the shooter using unregistered guns. "It is a frightening warning and a last call to all competent institutions to do more to prevent violence in society, including even more rigorous control of gun ownership," he said.

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