FOX 10- The Valley is already on edge because of several incidents involving exploding flashlights. But now we get word of 3 other incidents in just the past two weeks.

"People have created water bottles that explode," says Phoenix Police Sgt. Tommy Thompson.

And Phoenix Police say in one of those cases -- three of these exploding bottles were left outside someone's home.

So far no one has been hurt, but Thompson says whoever is doing this is using chemicals that could harm them or someone else.

"They'll mix chemicals that cause gas which expands in the bottle which eventually causes it to rupture, which makes a loud popping sound."

You may have done something like this in your science class, or watched an online video about it.

Police aren't connecting these incidents to any of the flashlight bombs. They think maybe it's a prank or a joke.

But officers say this is no laughing matter.

"Keep in mind, if you create this you're actually committing a class 4 felony which could have lasting repercussions," says Thompson.