ORLANDO (MEDIA GENERAL) – Social media is reacting to the worst mass shooting in U.S. history.

Fifty people were killed and 53 more injured in a shooting early Sunday morning at Pulse nightclub in Orlando.

#PrayForFlorida and #PrayForOrlando were among the trending hashtags on Twitter.

Brian Reagan, a manager at Pulse, called the shooting “unthinkable,” saying it “cannot be real.”

Sports teams and celebrities were also quick to comment on the tragedy and offer condolences.