Police said Saturday that at least seven people were killed in an explosion at a gas station in a small village in northwest Ireland, as rescue workers combed piles of rubble for more victims.

Irish Prime Minister Micheál Martin predicted that the death toll would rise.

“(It’s) a shocking toll, and there will be more,” he said. “It’s now a search operation, and we hope and pray.”

Four people were confirmed dead overnight by Irish police, adding to the initial toll of three from Friday’s explosion in Creeslough, County Donegal. After a blast ripped through the Applegreen service station in the 400-person community, eight people are in hospitals and several are missing.

“The search and recovery for additional fatalities continues,” said An Garda Siochana, the Irish police force. The cause of the explosion is being investigated.

Emergency personnel from Ireland and neighboring Northern Ireland have been called in to assist in what police described as a “search and recovery” operation. Sniffer dogs combed the debris, and a mechanical digger removed piles of rubble.

The explosion destroyed the gas station building, which houses the village’s main shop and post office, and damaged an adjacent residential building.

According to the prime minister, it was one of the “darkest days for Donegal and the entire country.”

“People all over this island will feel the same sense of shock and utter devastation as the people of Creeslough as a result of this tragic loss of life,” Martin said.

Agriculture Minister Charlie McConalogue, who represents Donegal in Ireland’s parliament, stated that the service station was well known throughout the country due to its prominent location on the main N56 road, and that it was “the heart” of the local community.

“People are shocked and numbed,” he told RTE in Ireland. “People have come together, and everyone’s concern is for the families of those who have lost loved ones, and how they can support them in the coming days.”