Almost immediately, Twitters users lashed out at his tasteless post.
"What is wrong with people?," commented one.
Another wrote: "A concert packed with kids who would've been excited for this night out. Some won't return. You think this is appropriate for a joke?’"
"What sort of human thinks that's an appropriate tweet?! Disgusting behaviour," said another.
Rather than apologise for his tweet, Leavitt followed up with a second.
"Honestly, for over a year I thought an Ariana Grande was something you ordered at Starbucks," he wrote.
Thousands of Ariana Grande fans fled Manchester Arena in terror after “loud bangs” were heard at the end of the show, The Sun reported.
Police confirmed there were a number of fatalities and it's being treated as a suspected terror incident.
Fans took to social media to document the hysteria surrounding them as the deadly blast took place.
Billboard has confirmed that Ariana is ‘okay’ after the incident.