An explosion Saturday in a Minnesota mosque was caused by an improvised explosive device, an FBI official said.
No one was injured in the blast at the Dar Al-Farooq Islamic Center in the city of Bloomington.
Rick Thornton, the FBI's special agent in charge of the investigation, told reporters, "At this point, our focus is to determine who and why. Is it a hate crime? Is it an act of terror? ... That's what the investigation is going to determine."
The Department of Homeland Security released a statement saying it was in "close contact" with federal, state and local authorities as the investigation continued. It said the department "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 statement continued, "We are thankful there were no injuries, but that does not diminish the serious nature of this act."
The explosion took place shortly after 5 a.m. when a few worshippers were present.
The manager of the mosque earlier called the incident an attack and said he suspected a man who was spotted outside the mosque at the time of the explosion might be involved.
Device tossed through window
Speaking to VOA Somali, executive director Mohamed Omar said, "A congregant saw a man driving a pickup truck, then heard a sound of a banging car door, before smoke came out and a huge explosion followed.
"The worshipper saw the man in a truck, whom we suspect was behind the attack. The exploded device was hurled into the window of the main office where the imam of the Mosque sits," and the suspect sped out of the mosque's parking lot just after the blast, Omar said.
A VOA reporter who went to the mosque reported that Bloomington police had cordoned off the entire area with yellow police tape and that fire damage was visible on the building.
Omar said that he did not know why his mosque had been targeted, but that the center had received threatening, anti-Islam and hateful phone calls and emails in the past.
"Our center is one of the Islamic centers that have been receiving threatening calls in the past, but I do not know another reason that can make us a target," he said.
The Council on American-Islamic Relations said attacks against Islamic institutions in the United States nearly doubled in the first half of 2017 compared with a year earlier.
Minnesota's CAIR chapter and the Muslim American Society have each offered a $10,000 reward for information leading to the arrest and conviction of the Dar Al-Farooq attacker.