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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It's the largest Eid event in Europe, and today's figure smashed last year's record 88,000 people in attendance.
Cloudier to the south with light and patchy rain at times.