AUSTIN, Texas (CBSNewYork/AP) — Tensions in Austin, Texas came to a boiling point Tuesday night when a man was burned by an incendiary device at a Goodwill store, but police and federal authorities said the blast wasn’t related to recent bombings that have killed and injured people and sparked panic across the state’s capital for weeks.

Officials responded to the Goodwill store near the intersection of Brodie and West Slaughter Lanes, where they discovered a man in his 30s injured by the device, which police say appears to be an old military-type ordinance.

He was rushed to St. David’s South Austin Hospital with serious but non-life threatening injuries, according to authorities.

The device was left in a box that someone had dropped off at the store’s donation site, CBS News’ Pat Milton reported. As an employee was sorting through the items, authorities believed the device ignited and burned him.

The scare came hours after a package exploded at a FedEx distribution center in Schertz, Texas around midnight Tuesday, hurting one person.

Investigators do not believe the incident on Brodie Lane to be related to the previous bombings, Milton reported.

In all, two people have been killed and four others seriously wounded in the previous blasts.

Schertz Police Chief Michael Hansan said the package that detonated early Tuesday had been traveling along an automatic conveyor belt when it exploded. A FedEx employee apparently suffered a non-life-threatening “percussion-type” injury from the blast.

“It is very early in the investigation, obviously. But we are confident that neither this facility nor any location in the Schertz area was a target,” Hansan said.

Texas’ attorney general said the package was sent from Austin and was addressed to a home in Austin.

Attorney General Ken Paxton also told television station KXAN that a second parcel bomb that didn’t explode was found at the FedEx facility. San Antonio Police Chief William McManus told a news conference there that the second package was no longer at the facility.

The FBI and ATF are at the scene.

“We can confirm that a single package exploded while in a FedEx Ground sortation facility early this morning,” a FedEx spokesperson told CBS News. “We are working closely with law enforcement in their investigation. We are not providing any additional specific information about this package at this time.”

An FBI agent told CBS News that “it’s more than possible” that the package is related to the Austin explosions, where two people and four others injured since March 2.

Two bicyclists were hurt Sunday night in Austin when police say they hit a wire that was placed along a street, triggering a blast.

Police said it suggests a “higher level of sophistication” than they have seen before in three early package bombs that were left on doorsteps.

“The belief that we’re now dealing with someone who is using trip wires shows a higher level of sophistication, a higher level of skill,” said Police Chief Brian Manley. “He’s either practiced a heck of a lot in rural Texas getting this right, or it’s a learned skill, perhaps something he’s acquired on the battlefield.”

Authorities repeated prior warnings about not touching unexpected packages and also issued new ones to be wary of any stray object left in public, especially one with wires protruding.

Local and state police and hundreds of federal agents are investigating, and the reward for information leading to an arrest has climbed to $115,000.

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)