Authorities are investigating a series of incidents in which homemade bombs were placed in rural mailboxes, causing one to blow up.

According to the La Crosse County Sheriff’s Department, three improvised explosive devices were discovered in mailboxes in the towns of Barre and Hamilton on Saturday and Monday. Only one of the three caused extensive damages while another burned the inside of a mailbox.

All three incidents are believed to be related, according to Capt. Kurt Papenfuss of the sheriff’s department, and it’s believed the devices were placed during nightfall. Authorities have no suspects at this time, and no one was injured in any of the incidents.

Papenfuss said none of the explosive devices were set to go off by being triggered or by remote control but instead had a fuse that was lit.

“I think the people doing it think it’s kind of fun and adventurous, but obviously someone is going to come out and check their mailbox,” Papenfuss said. “There’s minimal risk at 1 or 2 in the morning, but if you saw the one (mailbox), there was shredded metal. And shredded metal can certainly shred human skin and cause very, very serious injuries.”

Papenfuss said evidence — including the devices, fingerprints and tire impressions — have been collected and were to be sent to the Wisconsin Crime Lab in Madison on Tuesday. The United States Postal Inspection Service has also become involved as the matters are federal offenses.

The first explosive device was reported at 11:27 a.m. on April 12 after a resident on Highway OA went to retrieve the mail. The Dane County Bomb Squad responded to the scene, discovered the device was an explosive and disarmed it. Papenfuss said it’s believed the device did not explode because it was either not lit properly or did not stay lit.

A second device exploded at 12:45 a.m. on April 14 in a mailbox on Pleasant Valley Road, causing extensive damage to the box and post. Papenfuss said the explosion blew off both ends of the mailbox and scattered debris up to 20 feet away, causing a fire. The homeowner was awake when the explosion took place and notified authorities.

“It just demolished the mailbox,” Papenfuss said.

The third explosive device was reported at 1 p.m. later that day on Drectrah Road when a postal carrier was delivering mail. Papenfuss said the third device was ignited but only burned inside the mailbox, causing minimal damage.

Papenfuss said initial investigation indicates all three incidents are related due to the proximity to each other and the material used to make the explosive devices. The third device appears to have included something similar to a road flare, while the other two appear to have similar components, he said.

The incidents have prompted a federal investigation as well. Jeff Long, a postal inspector and public information officer with the U.S. Postal Inspection Service, said blowing up mailboxes is taken seriously.

“Where we get involved is when devices like this are placed in mailboxes,” Long said. “Once they start doing that, it comes into our backyard.

“We take it very seriously. We’re concerned for the safety of our carriers and the people getting the mail.”

Destruction of a letterbox is a federal crime, Long said, and is punishable by up to three years in prison.

The St. Paul-based U.S. Postal Inspection Service covers Minnesota, North Dakota, South Dakota, Nebraska and western Wisconsin. Long said the region does not see many incidents where explosives are placed in mailboxes, but he said investigations usually identify who was responsible.

The mailbox on Pleasant Valley Road is on the route of the West Salem Post Office while the other two are on the routes of the La Crosse Post Office.

West Salem Postmaster Ray Johnson said the incidents don’t appear to have been meant to be life-threatening, but it is still bothersome.

“Still, it’s a major concern,” he said. “I guess the common baseball bat just isn’t as exciting anymore.”

Papenfuss encourages anyone who has information related to any of the incidents to call the La Crosse Crime Stopper Tip Line at (608) 784-TIPS or the La Crosse County Sheriff’s Department at (608) 785-9629.