The parcel exploded at a facility in the town of Schertz, in the San Antonio area.
In a statement on social media, the Schertz Police Department said one person received medical attention at the scene.
However, the Houston Field Division of the Bureau of Alcohol, Tobacco, Firearms and Explosions said on Twitter that no injuries had been reported.
The explosion came as hundreds of police officers and FBI agents searched for the perpetrator of Sunday’s blast in Austin — the fourth this month — left two young men seriously injured and the city on edge.
Police said that blast was connected to three previous bombings in Austin. They said bomber used a tripwire in Sunday’s attack.
“We’re clearly dealing with what we expect to be a serial bomber at this point,” Austin police chief Brian Manley told reporters.
But Manley said police have been unable to determine a motive for the bombings.
The four blasts in Austin killed two people in the city of nearly one million people and injured another four.