Two men were arrested on Friday in northwest Ireland in connection with an explosion at a petrol station in 2022 that killed 10 people aged between five and 59.
Irish police said it arrested two men in their 50s as part of their investigation into the blast, which at the time they had called a "tragic accident".
According to the Irish Times newspaper on Friday, "no planned or deliberate criminal activity is being investigated" by the police in the case.
"Instead, the manner in which the gas system was being run and maintained is at the centre of the criminal investigation," said the paper.
Four men, three women, two teenagers and a five-year-old girl were killed in the blast in the County Donegal village of Creeslough on October 7, 2022.
Two two-storey residential buildings behind the petrol station collapsed.
The facade of a similar adjacent building was blown off by the explosion, which witnesses described as like a bomb.
Creeslough is around 30 miles (50 kilometres) from the border with Northern Ireland and has a population of about 400 people.
"It's a very dark day for the people of Donegal and for Ireland," said then prime minister Micheal Martin the day after the incident.
"The scale and enormity of it. It's such a small community, it means that almost everybody will know on a friendly basis people who've lost their lives," he said, speaking at the scene.