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.
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Peers have rejected to vote through the Government's Brexit Bill in the first major setback for the legislation.
Teresa Dennett needed emergency surgery but she died after a row over hospital catchment areas and because of a lack of critical care beds.
The move will put 400 jobs at risk.