The allegations began with a threatening letter and two prank calls to the Whitehouse High School office.
Two boys, ages 15 and 16, were arrested there last Thursday. They're charged with conspiracy to commit an act of a prohibited weapon -- a 2nd degree felony. That means the students are accused of threatening to bring a weapon to school.
Two more students, ages 14 and 15, were arrested yesterday, charged with making terroristic threats.
All four students were taken into custody at the Smith County Juvenile Attention Center.
"We found that there were some credible statements that we really did not feel comfortable with," Christopher Moran, the school principal, said.
Last Thursday, federal agents say they searched the entire campus and found nothing they deemed to be threatening. Moran says the school is safe and has placed no new rules or restrictions on the students.
But one week later, today, parents and students we talked to are still on edge.
"I'm fearful," Tammy Perry, a parent of a 9th grader, said. "I'm very fearful, but I do tell my son, you know, you can never be too careful in today's society, you just can't."
"There were a lot of students that were afraid to come to school," Tiffany Bachmeyer, a senior, said. "I was particularly am scared because you don't really know what's going on through a lot of these kids' minds that go here."
Bachmeyer says she's even changed her behavior.
"I'm trying to be a lot nicer to a lot of people that I'm normally like not nice to or just don't ever talk to," she said.
Local police are also taking the threats seriously.
"It is kind of difficult imagining something happening in a town the size of Whitehouse, but it goes to show that the potential threat for that happening anywhere -- it can happen anywhere, basically," Stephen Snyder, the detective on the case, said.
In an attempt to calm fears, Moran says school guards are on alert and security is heightened.
ATF and Whitehouse police are continuing to investigate this case, so they're not releasing any details about the threats at this time. The four students are expected to be arraigned within the next week, so we should know more at that time.