A fifth mail bomb has exploded in San Antonio

A PACKAGE bomb containing nails and shrapnel that was destined for an address in Austin, Texas, has exploded at a FedEx Corp distribution centre in San Antonio, injuring one employee, San Antonio fire officials say.

That blast came two days after the latest of four powerful homemade bombs set off in Austin this month, which killed two people and injured six more in what police warned appeared to be the work of a serial bomber.

The package exploded shortly after midnight local time at a distribution facility in Schertz, Texas, outside of San Antonio, about 105km south of Austin, the San Antonio Fire Department said on Twitter.

Agents from the Federal Bureau of Investigation and the Bureau of Alcohol, Tobacco, Firearms and Explosives were on the scene and investigating, fire officials said

They did not give further details of the address to which the package was bound. Police did not immediately say if the explosion appeared to be linked to the four prior blasts.

The first three were parcel bombs dropped off in front of homes on Austin’s east side, with the fourth an apparent trip-wire device that went off on the city’s west side on Sunday.

Those four devices were similar in construction, suggesting they were the work of the same bomb maker, officials said.

Anthony Stephan House, 39, died on March 2 and Draylen Mason, 17, died on March 12 when package bombs were left at their respective homes.

US President Donald Trump has been attacked for not commenting on the bombs, where some of victims have come from Austin’s historically black and Latino neighbourhoods.

“Can you imagine bombings occurring in McClean, Georgetown, Loudoun or Tyson’s killing and injuring white people and any suspicion of it being a person of colour or Muslim,” the NAACP_Loudoun tweeted. “The National Media, namely Fox News, and the Tweeter in Chief would be apoplectic.”

FedEx officials could not be reached for immediate comment.