Ireland's Olympic bronze medallist Michael Conlan's older brother, Jamie, was due to be weighed in at the event in the Regency Hotel yesterday but pulled out of his fight after suffering a shoulder injury in training three weeks ago.
Yesterday's weigh-in for the 'Clash of the Clans' boxing tournament at the Regency Hotel was being held ahead of six fights due to take place in Tallaght tonight.
The event has now been cancelled after gunmen opened fire as the fighters were standing on the scales to declare their weight ahead of the fights.
Promoted by Frank Warren and Macklin's Gym Marbella (MGM), the fights were expected to reach a global audience on the Box Nation channel.
The headline bout was to be between the Irish boxer Jamie Kavanagh and Antonio Joao Bento for the vacant World Boxing Organisation (WBO) European title.
That fight, and another between Gary Corcoran and Danny Butler, was to be broadcast live.
Kavanagh confirmed on Twitter that he escaped unhurt last night.
MGM is run by boxer Matthew Macklin (33), a former European middle-weight champion who is idolised by members of the Kinahan crime syndicate. His gym is based in Puerto Banus, on the Costa del Sol in Spain.
The Kinahan cartel is considered the most powerful drugs importation mob in the history of the State, which some estimate could be worth up to €1bn. Christy Kinahan (59) is the leader of the cartel but is rarely in Ireland, as he spends most of his time in his €6m luxury villa on the Spanish coast.
Macklin is not involved in crime but has friendships with leading members of the Kinahan gang.