The most recent was found Friday, and detonated by a police bomb squad at Newhall Community Park.
That pipe bomb was found by a jogger along a trail near Turtle Creek Road.
On Wednesday, two other pipe bombs were found nearby. About 25 police officers spent the weekend searching for more explosives, using specially-trained dogs.
People are being warned not to pick up any objects that don't belong to them and police have no suspects in their investigation.
