UTV News Editor Chris Hagan says that police were investigating reports of an illegal parade in Lurgan, County Armagh when the explosion took place.
Police say they were in área of blast at time, investigating reports of illegal parade. No injuries
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It will be increasingly humid and thundery with highs of 30C or more today.
Holidaymakers in Tunisia are determined not to be beaten. But, as Neil Connery writes, it won't be easy to escape the shock of the massacre.
Drink lots of water, stay out of the sun during the middle of the day, and take particular care of vulnerable people.