As promised, Firefly Music Festival organizers teased a portion of this year's lineup during the Firefly First Look concert Sunday night at the Trocadero.

Officially confirmed for Firefly 2015 are Elliphant, Run the Jewels, Spoon, Empire of the Sun and Bastille in addition to Chiddy Bang and Cheerleader who played the First Look event.

The full Firefly lineup is expected to finally make its appearance this week.

Sunday evening's free preview show, the first time the festival has thrown such an event, featured confirmed Firefly performers Chiddy Bang and Cheerleader — both Philly-based acts.

Firefly 2015 will take place at the Woodlands of Dover International Raceway in Dover, Del. on June 18-21.