It is understood the incident was not a car bomb attack, with officers believing a small-scale device was used.
A Police Service of Northern Ireland spokesman has said:
A number of businesses and streets in the Cathedral area of Belfast have been cordoned off following a small explosion.
It occurred at about 6.45pm as police were checking reports of a suspicious object.
At this stage there are no reports of any injuries.
More top news
Paramedics attended a scene in Willesden, north-west London, on Monday afternoon where they found the teenager with stab wounds.
The popular game relies on Google Maps, a problem in South Korea as those functions are limited by the government.
A Met Office warning covering much of England and south-east Wales is expected to remain in place until 11am.