Emma Salomonsson, 27, was shopping in the H&M clothing shop next to the store hit by a truck on the pedestrianised Drottninggatan in central Stockholm, shortly before 1pm Irish time yesterday.
At least four people were killed in the incident, which Swedish Prime Minister Stefan Lofven said bore the hallmarks of a terror attack.
“I just heard a big bang and turned around,” said Ms Salomonsson, a former professional footballer who was once part of the Republic of Ireland squad.
Ms Salomonsson said she came outside to see the truck smashed into the front of an adjacent store.
“I heard screaming, and someone said ‘he’s got a gun’,” she said.
She fled back into H&M and left via a rear exit, only to see crowds of panicked shoppers fleeing towards her.
Assuming the person responsible for the attack was chasing the crowd, Ms Salomonsson and a group of others returned into H&M and came back onto the street where police had arrived.
By now the truck had caught fire, and Ms Salomonsson smelt burning. “It was like fireworks, and then someone screamed that there was a bomb so we ran away,” she said.
Special forces police arrived on the scene and directed the crowd to leave the area.
“I was terrified. I was in shock and was just trying to understand what happened,” said the special needs assistant, whose mother is from Westmeath.
Taoiseach Enda Kenny last night said that Ireland stands with Sweden “in united determination that our values will not be defeated”.
“The cowards who perpetrated this attack place no value on our freedom and way of life here in Europe and their view has no place in our society,” he said.
Meanwhile, Mr Kenny said the US airstrike on Syria was a “matter of grave concern”.
Speaking in Berlin during a trade mission to Germany, Mr Kenny said the chemical weapons attack which the Assad regime has been accused of is a “war crime”.
“This is a matter of grave concern internationally in terms of politics,” he said.
“And obviously the American government made its decision as a reaction to the illegal use of chemical weapons. In my view the use of chemical weapons is a war crime.”
He added that the use of such chemicals is “an act of aggression that is beyond anything to do with what you might call conventional warfare”.
“Clearly warnings were given by the American government to those in the vicinity of the particular base that was bombed last evening,” he said.