Police investigating the Westminster attack say they've made two more 'significant' arrests overnight.
Nine people are now in custody.
The fifth person killed has been named as 75-year-old Leslie Rhodes from south London.
Scotland Yard have also revealed that the terrorist, Khalid Masood, was born Adrian Russell Ajao.
He was shot dead by British police yesterday after he mowed down pedestrians and stabbed Police Constable Keith Palmer near the Houses of Parliament.
Dozens were injured including an Irish person but it's been confirmed the Irish victim's condition is not life threatening.
One victim has been named as Kurt Cochran, an American tourist who'd been celebrating his 25th anniversary with his wife Melissa. She was also injured in the atrocity.
The Met police say Masood had been "known by a number of aliases ... was not the subject of any current investigations... There was no prior intelligence about his intent to mount a terrorist attack".
However he did have a wide range of convictions including assault, public order and possession of offensive weapons.
Meanwhile the Tainiste and Justice Minister Frances Fitzgerald has moved to reassure people here about security, in the wake of the Westminster attack.
"There are a small number of people here who's activities are a cause of concern in terms of supporting terrorism and they'll continue to be monitored by the authorities. But today is really about expressing our sympathy to all who've been affected by this appalling outrage in London."