One person has been injured after a homemade bomb containing nails and shrapnel exploded at a Texas FedEx depot.
It is the fifth explosion in recent weeks, with a serial bomber suspected of planting four powerful bombs in Austin that have killed two people and wounded four others.
An FBI spokeswoman confirmed to CNN that the incident could be connected to the other attacks.
The package exploded shortly after midnight local time at a distribution facility in Schertz, Texas, about 65 miles south of Austin, the San Antonio Fire Department said in a Tweet.
One employee at the FedEd facility was injured when the medium sized package - that was bound for Austin - exploded.
The FBI and bomb squads were at the scene.
FBI San Antonio spokeswoman Michelle Lee said: “Based on preliminary information gathered at the scene, there could be a connection with the four recent Austin explosions.
"We suspect it is related to our investigation," she added.
Three of the devices detonated were parcel bombs dropped off at night in front of homes on the city's east side.
The fourth was a tripwire device that went off in a west side neighbourhood on Sunday.
All four devices were similar, police said on Monday.
