There was a lot of fear and concern at Aragon High School in San Mateo on Wednesday.
"They don't know what to do, don't know what's happening, don't know if they're going to go to school tomorrow," said student Ryan McAuliff.
The buzz and worry centered on what was posted on the high school Facebook "confession" page earlier in the morning. The post threatened violence at Aragon on Thursday.
Parents are shaken up, too.
"People are not going to be sending their 8-year-olds to school tomorrow at Baywood elementary which is right next door out of concern for bullets," says Stacy Alexander, mother of a grade school and middle school student.
Police say they are taking the threat very seriously and will increase police presence at the school Thursday, though there is some indication this may be a hoax, says San Mateo police Sgt. Dan Noris.
"So to give a threat like this and to give time and preparation available to the police department to prepare for the eventuality of that type of action would be very unusual," Noris said.
Facebook confession is a page where people can go and post a problem anonymously, and others can offer help. But the question is, what has social media become for young people? The answer seems to be that it can often be a double-edge sword.
Stanford University professor Clifford Nass, who specializes in the psychology of technology, says Facebook, Twitter and other social media sites lead to fewer face-to-face interactions for young people.
"So those interactions become extremely stressful. On the other hand there is pressure on social media to be more positive -- on Facebook for example. So the only place they can express their negative feelings become these anonymous sites," Nass said.
But McAuliff, the student at Aragon High, points out help can be anonymous, too.
"People from Aragon or other students from other schools can give them feedback and help them out," he said.