At first, they say, it seemed like just part of the music.
It was a Saturday night and the dance tracks had been pounding at the Pulse Orlando nightclub, which calls itself the city's hottest gay bar. A sharp, staccato sound, arriving shortly after 2 a.m. ET, didn't seem out of place.
"I thought it was a Ying Yang Twins song or something," club-goer Christopher Hansen told reporters. "It went with the beat almost."