The Federal Bureau of Investigation is offering rewards of up to $15,000 in the search for culprits in arson attacks at three Catholic churches in El Paso that largely serve Hispanics and migrants.

The first blaze was set outside the St. Matthew Catholic Church on May 7. Exactly a week later, incendiary devices were thrown at St. Patrick Cathedral, a spokesman for the Diocese of El Paso previously told NBC News.

Then, on June 15, firefighters encountered heavy smoke coming from the main sanctuary of St. Jude Catholic Church. They found a broken window near the chapel’s altar.