A series of threatening, anti-Islam flyers were found scattered in Revere, Mass., this week, including one reportedly slipped under the windshield of a Muslim man’s car.

Police are investigating the vague threats, most of which read, “All Muslims will be killed in America and Europe, and Muhammad the Prophet’s image will be burned unless ISIS surrenders within 72 hours!!!”

“We have to treat it with a level of legitimacy until we determine otherwise,” Revere Police Chief Joseph Cafarelli told ABC affiliate WCVB 5. “I hope to God it’s not. I hope it’s, you know, the ravings of a deranged person, but, either way, we need to address it.”

Many of the flyers were found near the Massachusetts General Hospital Revere HealthCare Center, reportedly all over the road. The MGH area is home to multiple Muslim-owned shops and eateries.

The threats first came to light Tuesday evening on Twitter.

These are being posted all over Revere.. Sad that I cant feel safe in my own city. Im disgusted pic.twitter.com/CB1qlMou0X — Mohamed (@brahskie) February 18, 2015

Revere police investigate after discovery of threatening, anti-Muslim notes http://t.co/oifeDfX0QH

pic.twitter.com/zkKDvDU3fG — Imraan Siddiqi (@imraansiddiqi) February 19, 2015

Twitter user @brahskie was among the first to publicly report the hateful messages.

“The note was found by my friend Ahmed’s aunt near the MGH center on Revere beach,” @brahskie told the Daily Dot via email. “She was in tears when she read it and brought it to him.”

“I was in the car with my friends Moustafa, Ahmed, and Karim when we read the note over again and realized how serious the whole situation was,” said @brahskie, who did not share his real name. “We have no idea who the left note or who would do such a thing.”

He said that the threats were widespread enough that they must have stemmed from an organized effort and not just a lone conspirator.

“Considering the extent of how many notes were found by other people,” he said, “I knew, [it’s] likely it was done by multiple people. We went looking around the area to try to find more notes as evidence for the police report but we couldn’t find any.”

Despite the threats, @brahskie says that Massachusetts is generally welcoming toward Muslims. However, recent world events appear to have changed that general sentiment.

“This is the first time I’ve seen something like this,” he says. “Our town is mostly accepting of different races/cultures. After the recent attacks made (Charlie Hebdo, Isis, beheadings) I have seen a little bit more animosity towards Muslims in general.”

Photo via M.e/Wikimedia Commons (CC BY-SA 3.0)