A package destined for Austin exploded at a FedEx facility in Schertz, Texas, northeast of San Antonio, overnight. The package was filled with nails and pieces of metal. Early reports indicate no FedEx workers were seriously injured in the explosion. Authorities are investigating whether the failed package bomb is related to the serial bombings across Austin, which have killed two members of prominent black families and injured six others since the first bombing on March 2. Authorities said Monday that the fourth explosion, on Sunday night, was set off by a tripwire, indicating a “higher level of sophistication.” Police are investigating whether the bombings are hate crimes.