The organizers of Boston's upcoming Straight Pride parade are calling on authorities to prosecute those involved in mailing them envelopes full of glitter.

The group Super Happy Fun America's parade will follow the same route as Boston's annual LGBT Pride parade.

(Related: Straight Pride parade's application approved; Milo Yiannopoulos to lead parade.)

Three members of the group called authorities to report that they had received envelopes filled with a “granular substance.”

The FBI, three fire departments and the bomb squad responded.

According to LT. Robert Roy of the Salisbury Police Department, the envelopes were filled with glitter and Bible verses.

Speaking with NBC News, John Hugo, president of Super Happy Fun America, described the incident as “an act of domestic terrorism” and called on authorities to prosecute those responsible.

LGBT activists have previously “glittered bombed” politicians opposed to LGBT rights. Utah Senator Mitt Romney and former House Speaker Newt Gingrich were glitter bombed for their outspoken opposition. An activist yelled “Feel the rainbow” as he glitter bombed former Pennsylvania Senator Rick Santorum in 2012.