Secret Service spokesman Edwin Donovan announced Thursday that a letter addressed to the president has been intercepted, and it may be contaminated with ricin, the same toxin detected on mail sent to New York mayor Bloomberg and his nonprofit, Mayors Against Illegal Guns, on Wednesday.

CBS News reports that both mailings were sent from Shreveport, La., on May 20 and contain threats of violence against anyone who tries to take the sender’s guns. “The right to bear arms is my constitutional, God-given right and I will exercise that right till the day I die. What’s in this letter is nothing compared to what I’ve got planned for you,” the letter sent to Bloomberg read. No one who has come into contact with the letters has been seriously hurt, but responding officers in New York “suffered some minor symptoms” from the poison.

The letter sent to President Obama is currently being tested by the FBI’s joint terrorism task force.