Eye-witness Tommy Byrne, who watched the tragedy unfold at Lough Ree in Co Westmeath as he was working on his camper van at the lough harbour, said a freak squall roared over the water shortly after the anglers set off.
“It was pretty calm when they got going, but maybe about 45 minutes after they went my dogs got a bit spooked because there was a big squall out in the lake,” he said.
“The dogs jumped into the van, and there were hailstones and a big wind came round.
“Shortly after that one the party came around and asked me if I saw the others. Bags were floating on the water and the alarm was raised at that stage.”
Mr Byrne said he remembered the group setting off like any bunch of anglers looking forward to a few day’s fishing.
Shortly afterwards, he found himself in the middle of the rescue operation, bringing one of the anglers into his campervan and wrapping him in a blanket until paramedics arrived.
“It just appeared to me that the squall got them, hit their boat and sank them. It was just a random freak accident,” he said.
“The conditions were nasty enough, but it wasn’t particularly wild. I honestly think it was that squall that caught them off guard - it could have happened to anybody. It was just one of those things that came out of nowhere.”
Mr Byrne, who has lived on the lough, added: “I remember looking out at the lake and seeing these big white horses of waves.
“The waves on the lake are not like sea waves where you get periods in between, they can be very close together, and they can be violent. They were in a small boat and if one of those waves hit the boat...”
Martin McEnroe, of the Angling Council of Ireland, was at the lough shore to comfort loved ones of those lost in the tragedy.
“They are very, very upset, as you can imagine” Mr McEnroe said.
“It’s the worst tragedy that we can remember in angling circles on Lough Ree.
“Certainly we’ve never experienced anything like this before. It’s a huge, huge blow to us.
“The angling community in Ireland is a small community, and our hearts go out to the families and friends of the anglers that have been lost.”
Mr McEnroe said three of the experienced angling party had set out in one boat to an agreed camping site at Carna Bay yesterday, while the other three remained behind to load up the other boat.
Despite apparently calm conditions at the harbour, there can be five and six foot waves further out on the lake, he said.
The Garda Water Unit, the Fisheries Board, the RNLI, Athlone Sub Aqua club, anglers and locals all battled wet and blustery conditions during the day in the search for the remaining person.