Detectives are also appealing to the public for information about a silver Ford Transit van
Gardaí investigating a fatal shooting at a hotel in Dublin yesterday say they are aware of speculation about a retaliatory attack.
They are also appealing for information information about a silver Ford Transit van believed to be connected with the killing.
32-year-old David Byrne from Crumlin was shot after a gang, armed with automatic weapons, stormed the Regency Hotel in Drumcondra during a weigh-in for a boxing match.
Two other men in the hotel at the time were also injured in the attack.
Detectives say they believe at least six people were involved - three were dressed as uniformed gardaí, while one was disguised as a woman. Another man is said to have been wearing a peaked cap.
Investigating gardaí are also appealing for information about a silver Ford Transit van, which they say was later found burnt out in the Charlemont Estate in Marino.
Assistant Garda Commissioner Jack Nolan, says security checkpoints have been put in place for fear of a retaliation:
Last night, additional security checkpoints were put in place around Dublin city in response to the attack.
Nolan says they believe gunmen are still at large in the community:
This eye witness was at the weigh-in, and explained how the crowd ran after seeing gunmen with AK-47s:
Young children were among those forced to dive for cover during the incident.
Up to 300 fans were at the event at the busy hotel.
Tánaiste Joan Burton has said she was horrified by the shooting, and expressed her sympathy for those caught up in the incident.
Gardaí said emergency services found three injured men at the scene, all in their 20s or 30s, and that one was subsequently pronounced dead.
The body of the dead man was seen slumped against the hotel's reception desk.
The other two were taken to hospital with suspected gunshot wounds, but their injuries are not thought to be life threatening.
The shooting is reported to be linked to a gangland feud.
Footage emerged of the attack, which appears to begin as the weigh-in ended.
Today's Clash of the Clans boxing event at the National Arena has now been cancelled, tweeted TV channel Box Nation.
Mel Christle, president of the Boxing Union of Ireland, was on the podium with one of the boxers scheduled to fight when the gunfire erupted.
"There was a horrific cracking noise, in front of me, out of the banquet room - it was a place called the Regency Suite," he said.
"There was an incredible noise out there, and that is where I saw a body, a corpse, lying literally at the edge of the reception desk.
"So I'm sure he was trapped - he was riddled."
The main fight was due to be a European lightweight title bout between Jamie Kavanagh and Antonio Jao Bento.
Promoter Frank Warren was putting on the event with MGM, a Marbella-based gym run by Birmingham-born Irish boxer Matthew Macklin.
European light-middleweight champ Jamie Moore was shot in the legs two years ago while he was in the Spanish city training Macklin.