DUP MLA Jonathan Craig has condemned the blast in a busy area of Belfast city centre as "absolutely reckless".
UTV News reports him saying that there was "an explosion as the area was being cleared" and that it was a "miracle" if no one had been injured.
There is no confirmation of this from the police and there are no reports of any injuries, UTV says.
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Rain in the north tonight, cloudy and humid in the south
In an exclusive interview with ITV News, 100 metre world champion Justin Gatlin also said that booing at the World Championships "did hurt".
The 26-year-old had just given birth to her third child and was being transferred to a different floor when the tragedy happened.