The FBI and Massachusetts state police have launched an investigation after three members of a group that plans to hold a “Straight Pride Parade” in Boston next month reported receiving suspicious packages in the mail Monday. When opened, the packages were found to contain bible passages and glitter.

CBS Boston reports:

“Glitter bombing” is seen as an act of protest against those who oppose LGBTQ rights. It was often used by activists against Republican presidential candidates who campaigned against marriage equality.

Newt Gingrich 2011

Rick Santorum 2012.

Mitt Romney 2012

The Straight Pride Parade is expected to take place on August 31st.