Welsh mine deaths: Politicians pay tribute to miners
Assembly members have paid tribute to the four men who died in the Gleision mine disaster.
First Minister Carwyn Jones said Wales had hoped such accidents were a thing of the past.
Flags flew at half mast at Cardiff Bay and AMs began the first plenary session of the autumn term on Tuesday with a minute's silence.
Speaking in the Senedd chamber, Mr Jones said it was a "tragedy for Wales".
He sent his condolences to the bereaved families and paid tribute to the emergency services.
Rescuers "worked unstintingly, and at personal risk" to try to find the men who were trapped when a shaft at the drift mine flooded, he said.
Phillip Hill, 45, Garry Jenkins, 39, David Powell, 50, and Charles Breslin, 62, died at the Gleision colliery near Pontardawe.
Mr Jones said: "There was a time in our history when mining tragedies were sadly common.
"We had hoped that these events were in the past."
He added: "There were many things I thought I would have to deal with in the course of my role as first minister, but a mining accident was not one of them."
South Wales Police are leading an investigation into the disaster with technical support from the Health and Safety Executive, the first minister said. There is no timescale for the investigation.
Neath AM Gwenda Thomas was at the community centre in Rhos where the miners' families endured a long wait for news about the rescue attempt last Thursday and Friday.
"The atmosphere changed from hope to deeper and deeper anxiety, then to dread - absolute dread," she said.
Such accidents had become "a thing of the past", she said.
"This tragedy has however, brought back very painful memories to many of us."
On Tuesday morning she went to a secondary school - Ysgol Gyfun Ystalyfera - where two pupils had lost their father, she said.
Conservative assembly leader Andrew RT Davies asked for support to be made available for the families of the men who died and the three miners who escaped.
Plaid Cymru leader Ieuan Wyn Jones said the way people pulled together was "testament to the spirit that is in the local community".
Welsh Liberal Democrat leader Kirsty Williams said the accident was a "reminder of our shared history and the fact that no man should have to go to work, in whatever industry they are involved in, and not return to their families".
Meanwhile, an appeal fund to help the miners' families has now reached more than £70,000.