An improvised explosive device exploded early Saturday in a Minnesota mosque and community center. No one was injured, but the explosion damaged an imam's office at the Dar Al Farooq Islamic Center in Bloomington, located near Minneapolis. The FBI Minneapolis Field Office is now leading an investigation in cooperation with the Bureau of Alcohol, Tobacco, Firearms and Explosives, Bloomington police and other agencies. "The FBI said the preliminary investigation indicated the explosion was caused by an improvised explosive device, but would not characterize the device further," reports Peter Cox of Minnesota Public Radio. "They said their focus was to determine the 'who and why' behind the incident."Bloomington police said they received a call at 5:05 a.m. reporting an explosion. First responders arrived and "observed some smoke and some damage to a limited portion of the community center," Bloomington Police Chief Jeff Potts told reporters. Pictures from the outside show a broken window on the side of the building. The Muslim American Society of Minnesota posted pictures of the damaged office on its Facebook page:"One of our congregation saw a pickup truck leaving from the parking lot at a very unusual, you know, speed," said the mosque's executive director, Mohamed Omar. Faith leaders and community members gathered to denounce the attack. "An attack on a mosque is an attack on a synagogue is an attack on a church, is an attack on all faith communities," Curtiss DeYoung, the CEO of the Minnesota Council of Churches, told reporters. "And so we stand with you, a million protestants in Minnesota.""The Dar Al Farooq Center welcomes and expresses gratitude to members of different faith-based communities who turned up in large numbers to show their solidarity and support to us in our time of grief," the center wrote on its Facebook page, adding, "United We Stand and Divided We Fall."The center has received threatening calls and emails before, Omar told the Star Tribune. Callers have said "that we shouldn't be here, that we are a burden to the community or we are harming it," the newspaper reports.The Muslim American Society of Minnesota and the Minnesota chapter of the Council on American-Islamic Relations are each offering a reward for information leading to an arrest in the case. "CAIR has noted an unprecedented spike in hate incidents targeting Muslims and other minority groups since the November 8 election," the group said in a press release. Copyright 2017 NPR. To see more, visit http://www.npr.org/.