The mosque that Orlando nightclub gunman Omar Mateen attended was heavily damaged in an arson fire that Muslim leaders said was the latest incident in an escalating campaign of harassment and violence against the house of worship and its members. Given the timing — Sunday’s 15th anniversary of 9/11 and the start of the Muslim holiday Eid al-Adha — investigators believe the blaze that broke out shortly before midnight Sunday at the Islamic Center of Fort Pierce may have been a hate crime, St. Lucie County sheriff’s spokesman Maj. David Thompson said. No one was injured. The fire burned a...