A Florida man has been charged with threatening to kill Republican Rep. Brian Mast’s children over the treatment of illegal immigrants at the border.

The man, identified as Laurence Wayne Key, called the congressman’s Washington office, telling an intern who answered the phone, “I’m going to find the Congressman’s kids and kill them. If you’re going to separate kids at the border, I’m going to kill his kids. Don’t try to find me because you won’t.”

Key faces federal charges for the “communication of a threat to kidnap or injure a person.”

Mast has three young children.

Documents show that the intern reported the phone call to their supervisor. The FBI was made aware of the threat and began an investigation. Key was arrested shortly after allegedly making the threat.

In an interview with the FBI and a Martin County deputy, Key told investigators he did not threaten to kill Mast’s children, but said if Mast supports President Trump’s immigration policies, Mast should be separated from his children.

According to the criminal complaint, Key has called Mast’s office 478 times. He also reached out to the offices of Sens. Marco Rubio and Bill Nelson on Monday.

Key’s social media pages show his is an active Democratic Party volunteer in Marlin County and has also regularly volunteered for Planned Parenthood, WPTV reports.

The threat comes as several Trump administration officials have faced public harassment in recent days and on the heels of Democratic Rep. Maxine Waters (Calif.) calling on the public to “turn on” these officials and “absolutely harass” them wherever they see them.