Four Whitehouse High School students arrested earlier this month have been released from custody to their parents.
Two of the teens face second-degree felony charges of conspiracy to have a prohibited weapon at school. They've been expelled.
The other two students, whose charges have been upgraded from a misdemeanor to a state jail felony of filing a false alarm, allegedly threatened to detonate a bomb at school.
Investigators say they have not found any evidence the teens would actually carry out the acts.