The two men from Northern Ireland killed while working on a building site in Australia were from Co Tyrone and Co Londonderry.
The accident happened in East Perth where an apartment complex was being built, the construction company involved said.
It is believed the men were trapped under a large concrete slab which came off a lorry as a crane attempted to remove other slabs.
They have been named locally as Joseph McDermott from Omagh and Gerry Bradley from Portstewart both aged in their 20s.
The building site has been closed while a health and safety investigation is carried out.
Construction firm Jaxon said its thoughts and condolences were with relatives and friends of the two dead men.
The accident happened at about at about 11.30am eastern Australian time, 3.30am GMT.
The construction site on Bennett Street in the city was closed following the incident and the local coroner has taken control.
“Our heartfelt thoughts and condolences go out to the families, loved ones and colleagues of the two men involved in this tragic accident,” Jaxon said in a statement.
“Counselling support has been offered to all 52 employees and contractors who were on site today and also to Jaxon’s wider workforce.”
The construction company said it has been in operation since 1958 and has never experienced a fatality among its workers.
“Our workforce is grieving and our focus is on supporting the families and those affected. As a mark of respect, and to fully support our employees, all Jaxon sites will be closed tomorrow,” the company said.
“Safety is our highest priority. The accident is the subject of an ongoing investigation by the relevant authorities and it would be premature to speculate or pre-empt the findings of the investigation.”
The Department of Foreign Affairs in Dublin said consular staff were aware of the incident.
“The department is aware of the case and stands ready to provide consular assistance,” a spokesman said.
The Australian Broadcasting Corporation quoted one witness, Travis, who said the slab appeared to have fallen off a delivery truck while it was being unloaded.
He said he tried to help lift the panel.
“All I was thinking of was to just get the slab off him, so a whole bunch of workers jumped on one side of the slab, because it was sort of sitting on another slab, like a concrete barrier.
“A whole bunch of guys jumped on that side while a few of us lifted the other side ... so it was a couple of inches off them.”
Joe Byrne, a Social Democratic and Labour Party (SDLP) Stormont Assembly member representing West Tyrone, expressed his condolences.
“It is very sad news to hear of two construction workers from Northern Ireland being killed in Australia, a long way from home.
“I feel particularly sad that a 24-year-old man from Omagh was on a building site and was killed.
“Construction work is always dangerous, it is always more difficult for a family and community when the accident happens so far away.”