(CNN) -- Two teens who, in separate incidents, threatened to carry out similar attacks as the massacre in Newtown were promptly arrested this week -- a sign that law enforcement officials have taken an aggressive no-tolerance approach against potential copycats.
In California, Sergio Cabada posted messages online that he "both supported the actions of the school shooter in Connecticut and had thought of possibly committing similar acts," police in the city of Fairfield said.
Police learned of the statements about 9 a.m. Monday. By Monday afternoon, detectives had tracked them down to the 18-year-old in the northern California city of Suisun.
Cabada was arrested and faces felony charges of criminal threats, police said.
"Several items were seized from the residence in an effort to both complete the criminal investigation and to prevent any future acts of violence by Cabada," a police statement said.
In the second case, police in Tennessee arrested Shawn Lenz, 19, after he allegedly posted threatening messages on Facebook.
Lenz, in a post Sunday, wrote: "feel like going on a rampage, kinda like the shooting where that one guy killed some teachers and a bunch of students," CNN affiliate WSMV reported.
He was arrested the same day and charged with terrorism, harassment through the Internet and possession of drug paraphernalia, the affiliate reported.
The arrests come after investigators in the Connecticut elementary school shooting issued stern warnings to potential copycats.
Last week, Connecticut State Police Lt. J. Paul Vance warned that threats would be "investigated statewide and federally and prosecution will take place when people perpetrating this information are identified."
However, such arrests may prove difficult to prosecute, legal experts say.
"This country is based on freedom of speech," said Ryan Calo, a law professor with the University of Washington. "Saying things about the Connecticut shooting somewhat in a threatening manner, that is not going to be actionable, for the most part."
But, he added, "If you intentionally interfere with an investigation, mislead officers trying to conduct an investigation on purpose, well then, yes absolutely, you're going to be prosecuted."
There may be another way to prosecute suspects but that also raises issues, said Calo.
"Another is where you intentionally create a public panic," he said. "But understand what the prosecution would have to show is the post or the tweet was done intentionally, was done on purpose, in order to interfere with the investigation in order to create a public panic and that is a relatively high bar to show. "
CNN's Tina Burnside and Josh Levs contributed to this report.