The Exchange Street West area in Belfast where the explosion happened is close to many restaurants and bars.
The city centre was extremely busy with shoppers and festive revellers when the incident happened.
More top news
Pc David Phillips' widow broke down in tears as his sisters and best friend paid tribute to the "man they adored".
Merseyside police have released emotional new images of murdered PC Dave Phillips and his young family.
Warning issued after tourists seen walking on railway line used in the films by the Hogwarts Express.