A mosque and an Islamic community center in Silver Spring, Maryland, both received threatening letters, as three Jewish schools in the region also received threats.
The Islamic Education Society of Maryland received a threat Monday, Montgomery County police said. Officers were called about 5:30 p.m.
Someone opened the mailbox at the mosque on Veirs Mill Road and found a note offering money to anyone who "slaughtered Muslims," according to the Council on American-Islamic Relations (CAIR). The note showed two figures with arrows piercing their hearts, the advocacy organization said.
Another note was found Tuesday about 7 miles to the northeast, at the Muslim Community Center on New Hampshire Avenue, police said. Officers were called about 12:45 p.m.
These threats occurred as two Jewish schools in Maryland and a third Jewish school in Virginia received bomb threats on Monday, as News4 reported.
Students and staff members at Aleph Bet Jewish Day School in Annapolis, Maryland, and Gesher Jewish Day School in Fairfax, Virginia, were evacuated from the buildings after the threats. The Charles E. Smith Jewish Day School in Rockville, Maryland, also received a threat. Officials did not evacuate that school.
Someone placed an anti-Semitic call to the Charles E. Smith Jewish Day School about 9:30 a.m., Rabbi Mitchel Malkus said.
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"They said that there was a bomb on our premises and that Jewish souls would be destroyed," Malkus said about the message he said was made via a recording.
CAIR is calling for state and federal law enforcement to investigate.
"We urge federal, state and local law enforcement authorities to conduct a prompt and thorough investigation into this disturbing incident and to bring the perpetrators to justice," CAIR Maryland Outreach Manager Dr. Zainab Chaudry said in a statement.
Stay with News4 and NBCWashington.com for updates on this developing story.