As the sheriff's bomb squad worked to test the already detonated homemade bomb in front of a home on Palm Drive, concerned neighbors looked on.
"It's scary because I have a little 7 year old," said Karen Weaver.
Karen Weaver says a bomb went off Friday around 10:00 p.m.
"It was pretty loud to where it shook my window," said Weaver.
The bomb was placed underneath someone's car. In most cases, however, the sheriff's department says the culprit or culprits are leaving them in mailboxes.
"My mailbox is locked, so nobody can get to mine thankfully but when I see it happen right up the street from my parents, it's a little scary," said Michelle Ford of Yucaipa.
According to the Yucaipa Police Department, authorities have been investigating several reports within the past week. The bombs are crude, household items mixed in plastic bottles. They contain a chemical cleaner that when placed with tin foil cause the ingredients to explode when they're picked up.
"The bombs generally take a short time to go off but in some cases they fail to explode until the bomb is picked up, further agitating it, causing it to explode in the unsuspecting person's hands," a statement distributed Oct. 9 said.
"Fortunately no one's been injured. There was a very close call over the weekend where a citizen did remove the device from her mailbox," said Yucaipa Police Sgt. Fred Gonzalez. "After she placed the device on the ground, it did detonate. If she had been holding it when it detonated, it would have caused severe injuries."
The homemade bombs are a big concern for mail carriers as well.
"It's my worst nightmare," said mail carrier Mike Liles. "You open up one of those and it blows up! Where's it going to go? Right out the box and right into the vehicle, so yeah, it's really scary."
Meanwhile, as police work on a number of leads, residents can only wonder as to who's doing this, and why.
"I don't think there should be any tolerance for that. I think whoever is doing this should go to jail," said Kenton Vantassel of Yucaipa.
Yucaipa Police are warning residents not to "touch, pick up or kick bottles filled with unknown fluids or objects." Authorities are urging residents to call 911 immediately once they're a safe distance from the object.
Anyone with information regarding the chemical bombs is asked to contact the Yucaipa Police Department at (909) 790-3105.