A witness, Mark Ashbridge, took this picture of the small blast in Belfast city centre.
It appears people had been pushed back before the explosion occurred.
Mark says "the glow is the result" of the blast:
No injuries have been reported.
More top news
The Democratic presidential candidate may also have shown his cards on his choice of running mate.
The US president also shared a post on Twitter accusing Dr Anthony Fauci of misleading the public over hydroxychloroquine.
Fears over an impending second wave of coronavirus dominates Wednesday’s front pages.