ATF has taken evidence from the four blast sites in Austin, Police Chief Brian Manley said.
The explosive device was left in a box at the location, CBS News' senior investigative producer Pat Milton reports. One employee sustained minor injuries and was treated by paramedics on the scene and later released, the Schertz Police reported via Facebook.
Yet Kennedy said investigators may benefit from the recovery of one unexploded device that could provide a multitude of clues - from its engineering to the type of components used in its construction. Reyes says such military items are sometimes mistakenly donated to Goodwill rather than being properly disposed of.
The first blast of the day, reported about 6:44 a.m., killed a male teenager, later identified as Draylen Mason, and injured a woman in her 40s.
Authorities also closed off an Austin-area FedEx store where they believe the bomb that exploded was shipped to the distribution center.
Until now, the spate of blasts that began in early March had been contained to Austin, the state capital with a population of almost one million where two people were killed and several more injured.
Investigators later found an undetonated bomb disguised as a package at a FedEx store near the Austin-Bergstrom International Airport in Southeast Austin, and confirmed that a package delivery store in Sunset Valley is believed to be the source of the bomb that exploded in Schertz. "Local, state and federal law enforcement working hand in hand to get to the bottom of it", Trump said, in his first public response since the crime wave began.
But police could not say whether there was a link to the serial bombings and continued to process the scene late in the afternoon.
A package bomb has exploded at a FedEx distribution facility in San Antonio city in Texas, hurting one person, officials said today.
Lee says it is still early in the investigation, but "it would be silly for us not to admit that we suspect it's related" to the four Austin bombings that have killed two people and injured four others since March 2.
The Austin Fire Department initially said it was a reported package explosion.
He added that the person responsible for the bombings had previously been "very sophisticated in going around surveillance cameras". "We have to find this very sick person or people".
Hours earlier, a separate package exploded at a FedEx shipping center in Schertz, about 60 miles (96 kilometers) south of Austin.
In a statement Tuesday evening, the Federal Bureau of Investigation said no one was injured when law enforcement responded to a report of a suspicious package at the facility around 6:20 a.m. Although the latest blast did not inflict serious harm, it added to the widening fear of more strikes like those that have already killed two people and badly wounded four others. It was triggered along a street by a almost invisible tripwire, suggesting a "higher level of sophistication" than agents saw in three early package bombs left on doorsteps, according to Fred Milanowski, agent in charge of the Houston division of the Bureau of Alcohol, Tobacco, Firearms and Explosives.
"The bomber, I believe, wants to talk", he said. "But it also increases the likelihood that he would make a mistake". On March 18, two white men in their 20s set off an explosion, which authorities say was caused by a tripwire placed on a residential street. But William Grote told The Associated Press on Monday that his grandson was one of them and that he had what appeared to be nails embedded in his knees.
"The use of a tripwire is far less discriminating than leaving parcel bombs at residences and suggests that (Sunday's) victims were not specifically targeted", the global think tank Stratfor said in one of its Threat Lens reports.