The Taoiseach, Bertie Ahern, has said the killing of a young mother in Coolock yesterday was a 'new low'.
Mr Ahern also criticised what he said were excessively lenient sentences for serious offences, including murder.
Donna Cleary, 22, died after gunmen fired shots into a house in Coolock in north Dublin in the early hours of yesterday morning.
The Minister for Justice, Michael McDowell, said the killing was a watershed. Speaking this afternoon, Mr McDowell said people should reflect on the society we are living in.
He reiterated his plans to bring mandatory criminal sentences for firearms offences in the forthcoming legislation.
A team of 50 detectives are investigating Ms Cleary's murder. Four men and a woman were arrested at a house in Kildare last night. The five are in custody at Santry and Coolock Garda Stations.
Ms Cleary went to a 40th birthday party at the Innisfail GAA Club in Balgriffin on Saturday night before going back to a house party at Adare Green in Coolock.
At 2.30am, 30 minutes after some men were refused entry to the party, a car with three men inside pulled up outside the house.
One man got out, leaned on the car's bonnet and fired five shots from a handgun. One of the bullets hit Ms Cleary in the chest as she stood just inside the front door.
She collapsed and was pronounced dead in Beaumont Hospital two hours later.
Gardaí last night stressed the shooting was not drug related and was not linked to any feud.
Investigating officers say they want to hear from taxi drivers who brought people from the Innisfail GAA Club to the scene of the attack.
Prayers have been said in the local church for Ms Cleary's family.
