The incident, which took place in Sunningdale Gardens off the Ballysillan Road around 9.50pm, saw a man believed to be UDA ‘brigadier’ John Boreland shot dead.
Ms Long said she “utterly condemned” the killing.
“Murder is always wrong and there can never be any excuse for people bringing guns onto the streets. Yet another family will now have to bear the grief of a life lost and yet another community will be living in fear.
“That this murder took place in a residential street, placing the whole community at risk, further highlights the recklessness of those involved and the need for them to be taken off the streets.
“I would appeal to anyone with information on this attack to bring it to the police immediately.”