Hanford police, fire and the FBI are all still here investigating. No one was injured but it gave students and parents quite a scare.
Police markers were seen behind Hanford high school's auto shop where authorities say a small pipe bomb went off at about 12:15. Police say the small device was powerful.
Lt. Parker Sever, Hanford PD, says "It was a pretty crude device it appeared to be homemade in nature but still very dangerous."
The explosion happened in a fenced off area near the auto shop, away from people but it was loud enough that all 1,800 students on campus could hear it.
Miguel Torres, student, says "Ii was just like sounded like a car back fired that's what everyone was saying they thought it was."
Heather Ferraiz, student, says she heard "A big boom!"
Buses lined the west side of campus to pick students up early. Some parents rushed to campus and frantically called their children when they first got word of the lockdown.
Beverly Chavez, parent, says "It's scary. It's too close to home you just can't send your kids to school anymore you don't know what's going to happen."
Students hugged each other and called loved ones after they were kept inside their classrooms two and a half hours. Many said it was scary not knowing what was going on. "We're all kind of scared but pulling through so that's all we could do for our friends is pull through," says Ferraiz.
Police are reviewing school surveillance cameras to try and get as much information as they can.
No after school activities were canceled and school will resume as normal Friday.