Leaders of the Masjid al-Sahaabah mosque in Watauga, Texas, have grown accustomed to receiving several threatening voice mails on their answering machine each week.
Normally, the messages are deleted and quickly forgotten at the mosque near Fort Worth.
But a message that arrived one recent afternoon was different.
The caller identified himself as a local Army veteran and a Christian who was "armed to the teeth." Referring to Islam as a "violent religion," he accused Muslims of trying to import sharia law to the United States and called for "another Christian crusade."
"We will cut all of your heads off," the caller said. "Do you understand me? All of you."
The message wasn't discovered until a week after it was left, Simon Vincent, the head of mosque security, told The Washington Post.
Instead of deleting the recording, Vincent said, the mosque decided to report the incident to law enforcement officials and the media.
"Our community is fed up with this," he said. "During Ramadan, we had someone shining a laser sight from his rifle at the mosque as well."
A spokesman for the FBI's Dallas field office said the agency is working with local police and mosque officials to investigate the phone call, but he declined to comment to The Post on the specifics of the case.
Vincent said investigators have told him the call was made using Google Voice and that they are attempting to track it to an IP address and a home address.
"The person tried to hide, but they weren't that good," he said.
Vincent, a Marine veteran, suspects that the caller was merely posing as a veteran himself.
Watauga Police Chief Glen Fowler called the threatening voice mail a "significant incident" and said he has directed his staff to handle the case as a "priority investigation."
"We will continue to work diligently on identifying the person responsible for this horrific phone call," Fowler said in a statement, adding: "We value our relationships with the community, of which the Islamic Center is certainly a big part."
Alia Salem, executive director of the Dallas-Fort Worth chapter of the Council on American-Islamic Relations (CAIR), told The Post that the specificity of the message suggested that the caller was someone who had possibly "become radicalized."
"In our assessment, this was an actionable threat," Salem told The Post. "He's identified himself as being local to the area and given specific instructions about what he would do."
"The call starts off docile, but then it escalated," she added. "For us, it kind of gave us insight into the mentality of the person, which made us nervous."
Such calls are not entirely shocking, Salem said, given the anti-Muslim rhetoric being spewed by Republican presidential nominee Donald Trump and other conservative politicians and commentators.
"People think that if their lawmaker thinks or says something hateful, then that means it's okay," Salem said. "There have been no consequences for someone like Donald Trump, and he grows in popularity, which sends a clear message to people who espouse this type of bigotry."
Last November, after the deadly terrorist attacks in Paris, CAIR, the largest Muslim civil rights and advocacy organization in the United States, announced that it had received "more reports about acts of Islamophobic discrimination, intimidation, threats, and violence targeting American Muslims (or those perceived to be Muslim) and Islamic institutions in the past week-and-a-half than during any other limited period of time since the 9/11 terror attacks."
Weeks later, on Christmas Eve, Muslims in the Dallas-Fort Worth area were targeted in a violent incident. Anthony Torres is accused of opening fire on a Muslim-owned tire shop, killing one customer and injuring others, according to Fox affiliate KDFW.
Torres yelled "Muslim!" during the attack and expressed anti-Muslim sentiments to police after his arrest, the Dallas Morning News reported. He has been charged with a hate crime, as well as one count of murder and two counts of aggravated assault, KDFW reported.
The Watauga Masjid already had armed security, but it has been bolstered since the threatening voice mail was discovered, said Naeem Agha, chairman of the mosque's board of directors. The Watauga Police Department has also implemented additional patrols in the area.
Agha said the mosque - which has about 300 members and is located in a residential part of town - has received an outpouring of support, including a daily stream of visitors from the neighborhood and members of the police department, who have stopped in to express support, Agha said.
Even Christian volunteers have stood guard outside the mosque, he noted.
"The visitors say, 'We don't believe this person was a Christian because Christians don't do this,'" he said. "This phone call is not religion - this is a form of terrorism."
© 2016 The Washington Post(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)