One employee was injured when a package containing nails and shrapnel that was bound for Austin, Texas, exploded at a Texas FedEx facility, the local fire department said.
The package exploded shortly after midnight local time at a distribution facility in Schertz, Texas, outside of San Antonio, about 65 miles south of Austin, the San Antonio Fire Department said in a Tweet.
It was unclear if the explosion was related to a string of bombings in the Texas capital over the past two weeks that have killed two people and wounded four.
The first three devices in Austin were parcel bombs dropped off at night in front of homes on the city’s east side, with the fourth a tripwire device that went off in a west side neighborhood on Sunday. All four devices were similar, police said on Monday.
Investigators said they have no clear idea what motivated the series of attacks, which began 17 days ago, and have publicly reached out to the bomber, urging him or her to contact them and explain what his demands are.
The first three devices were parcel bombs dropped off at night in front of homes on the city’s east side, with the fourth a trip wire device that went off in a west side neighbourhood on Sunday. All four devices were similar, police said on Monday.
“We are clearly dealing with what we expect to be a serial bomber at this point,” Austin Police Chief Brian Manley told a news conference near the site of Sunday’s bombing.
Two men were injured on Sunday by the latest bomb, which police said may have been activated by a trip wire across a sidewalk. It was a more advanced design than the previous bombs.
The men, 22 and 23 years old, were taken to a hospital with what police described as “substantial” but not life-threatening injuries.
Manley said more than 500 federal agents were involved in the investigation, including from the Federal Bureau of Investigation (FBI) and US Bureau of Alcohol, Tobacco, Firearms, and Explosives.
“There is an army of law enforcement folks on the scene right now,” Austin Mayor Steve Adler said on CNN. “I am confident that we’re going to find whoever is responsible for this and then we’re going to stop it.”