The FBI has joined an investigation into a violent threat against a refugee community center in Aurora, Colorado.

The Mango House, which serves primarily Muslim immigrants, received two typewritten notes on Thursday reading, “WERE GONNA BLOW UP ALL OF YOU REFUGEES,” police spokesman Sgt. Chris Amsler told Reuters. Law enforcement did not find signs of explosives or suspicious devices on the premises.

The notes came the day before President Donald Trump signed an executive order suspending the U.S. refugee resettlement program and temporarily blocking all travelers from seven Muslim-majority countries. A draft of the order had been circulating online for days.

Mango House owner P.J. Parmar told CBS Denver that he believes the threatening notes, which an employee found in the parking lot and a stairwell, were fueled by the tense political situation.

“It’s a minority of the population of course, but that minority now has a vocal leadership in terms of Donald Trump, in terms of the rhetoric we saw during the campaign and in terms of executive orders,” Parmar said.

Those who work in Mango House declare that such hate only makes them more committed to their cause.

“It makes me want to stand up stronger and say no,” Carolyn Anello, who founded the facility’s dental clinic, told The Denver Channel. “These people are kind and loving, and if you get to know them, you will get to love them, just like I do.”

Mango House is a private business that rents to several tenants serving the local refugee community, including Anello’s clinic, a food bank, a refugee youth program and classes in English and U.S. citizenship, according to its Facebook page. Various cultural groups also use space at the facility for their events. The refugees who come to Mango House are mostly from the Middle East and Africa.