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An explosion from a bomb rattled a suburban Minneapolis mosque early Saturday morning, authorities said. There were no injuries, but a room in the building was damaged and worshipers were shaken.

The blast at Dar Al-Farooq Islamic Center in Bloomington happened just after 5 a.m. local time as the mosque was preparing for Fajr, or the early-morning prayer, the Muslim American Society of Minnesota said.

"Someone threw an explosive device and started a fire in the office of the Imam and President of the mosque," the society said. "The attendees put out the fire."

The FBI has taken over the investigation and Minneapolis special agent in charge Rick Thornton told reporters that the blast was from an improvised explosive device.

Mohamed Omar, executive director of the Islamic center, told reporters that a witness saw a pickup truck drive away after the device was tossed into the mosque.

A motive in the bombing, and whether it was a hate crime, has not been determined, Thornton said.

"The good thing in this event here is that there was no injuries," Bloomington Police Chief Jeff Potts said at a news conference. He said the police and fire departments responded to the call of an explosion at around 5:05 a.m. (6:05 a.m. ET).

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The federal Bureau of Alcohol, Tobacco, Firearms and Explosives is also on scene and involved in the investigation. Potts said it when first responders arrived there was smoke coming from the building and a limited amount of damage to the community center.

Local leaders and faith groups denounced the violent act.

Law enforcement officials investigate an explosion at the Dar Al-Farooq Islamic Center in Bloomington, Minnesota, on Aug. 5, 2017. Authorities say the explosion damaged one room but it didn't hurt anyone. David Joles / Star Tribune via AP

"We love our Muslim neighbors," Simon Trautmann, a city counselor, said at a news conference. "This is an attack on our community."

"An attack on any of a place of worship is an attack on all places of worship," Arthur Murray, the pastor of a Bloomington church, added.

The Muslim American Society of Minnesota is offering a $10,000 reward for information that leads to an arrest and conviction of those responsible, reported NBC affiliate KARE.

The Minnesota chapter of the Council on American-Islamic Relations also said it was offering a $10,000 reward.

People make phone calls as law enforcement investigate an explosion at the Dar Al-Farooq Islamic Center in Bloomington, Minnesota, on Aug. 5, 2017. David Joles / Star Tribune via AP

The center has received threatening phone calls and emails in the past, Omar told the Star Tribune.

It's usually "people talking about us, telling us, accusing us that we shouldn't be here, that we are like a burden to the community or we are like harming it," he said.

Trevin Miller, who lives across the street from the mosque, said the explosion woke him up.

"I felt it on my insides," he told the paper. "I have a daughter that usually lives with me, and to wake up to all this, it's like, what the hell, this shouldn't be happening right at our doorstep."

The Department of Homeland Security said in a statement that it was in contact with local and federal authorities as well as community leaders.

"The Department of Homeland Security fully supports the rights of all to freely and safely worship the faith of their choosing and we vigorously condemn such attacks on any religious institution," the department said. "We are thankful that there were no injuries, but that does not diminish the serious nature of this act."

Minnesota Gov. Mark Dayton thanked the officials who were investigating the attack.

"Every place of worship, for all Minnesotans of every faith and culture, must be sacred and safe. My prayers are with the children, families, and faith leaders of the Dar Al Farooq Islamic Center today," he said in a statement.

Lt. Gov. Tina Smith added that "though we do not know what happened this morning, or who was responsible, we all stand together for love and acceptance, and against hate and intolerance."

Bloomington is a city of around 82,000 south of Minneapolis.