Drivers along Redwood Road near Grove Way called CHP to report a strange looking white Styrofoam box along the roadway. The calls came in Monday evening around 5:30 p.m.
"Taped up with the only word exposed, 'dangerous,'" said Sgt. Michael Norton as he described the box.
"The box was being suspended by the string. The string ran off into the trees," added Norton. "It did look suspicious to us because we normally don't encounter unattended boxes along the side of the road. In addition to that, it was making a mechanical noise inside the box."
Someone found this box hanging from a tree in #CastroValley. @ACSOSheriffs bomb squad was called. The box said “dangerous” and made a humming noise. They destroyed it. Turns out it was a @SJSU Wx ballon. #abc7now pic.twitter.com/vvLL2V89cd— Katie Utehs (@KatieUtehs) August 8, 2018
After scanning it from a safe distance, Sgt. Norton decided to blow up the suspicious device. Only then did he learn what it actually was.
"Once I pulled it out of the tree, I saw that it was a weather balloon and then I realized all my buddies were going to give me a hard time," said Sgt. Norton.
The balloon came from San Jose State University researchers. They launch the equipment in order to measure the ozone layer. When the balloon pops, the equipment lands, hopefully protected by the Styrofoam box. People are asked to call them in so researchers can collect the equipment.
"The Ozone Project has been going on for month, so this is not something that just started and the first one fell out of the sky," said Professor Alison Bridger with San Jose State University.
What started as a science experiment turned out to be a lesson for all -- clear labeling matters.
"Here is my contact information. Here is my email address. We could have handled this in no time at all," said Sgt. Norton.
"I think that we're going to put the labeling more clearly on it and very official looking to emphasize this is gathering weather data and it's not dangerous," said Prof. Bridger.
The investigation did force the evacuation of some nearby homes and shut down a busy roadway during the commute. The research equipment lost in the explosion was worth around $1,000.