Under attack

A series of bombings that shook the Texan city of Austin could be a trial run for a bigger attack, a former FBI adviser has warned, as police urgently hunt for clues.

UNITED STATES: A series of bombings that shook the Texan city of Austin could be a trial run for a bigger attack, a former FBI adviser has warned, as police urgently hunt for clues after a fifth device exploded yesterday.

President Donald Trump called the perpetrator ‘‘sick’’ and said all resources were being devoted to tracking down the person or persons.

A Fedex employee escaped serious injury yesterday when a package exploded at a distribution centre in Schertz, San Antonio, 128 kilometres south of Austin.

Brian Manley, chief of police for Austin, said the package had been bound for the city. William Mcmanus, chief of police for San Antonio, said a second suspicious package found later at the facility had been removed. Hours later police were called to a Fedex site in Austin after reports of another suspicious package.

Michelle Lee, FBI spokesman for San Antonio, said they were linking the Fedex explosion to four other Austin bombings earlier this month. Officers from multiple agencies are working on the case amid fears that as time passes those behind the attacks would get bolder.

Randall Rogan, a Wake Forest University professor and an expert on forensic linguistic analysis, said he thought the perpetrator might soon make contact with the police or release a communique. Rogan warned that the complexity of the fourth bombing, triggered with a tripwire on Monday, might suggest it was a test run for something bigger.

Manley added: ‘‘Clearly we are dealing with a serial bomber.’’ He appealed to the perpetrator or perpetrators to make contact with the police.

Authorities are at a loss over the motive behind the bombings, which killed two members of the same predominantly black church – Anthony House, 39, who died on March 2 when he picked up a package on the front porch of his home, and Draylen Mason, 17, who died 10 days later. A 75-year-old Hispanic woman was seriously injured when she picked up a package on her front porch the same day. At first police suspected a racial motive, but that changed on Monday when a fourth bomb exploded and injured two white male cyclists.

An explosion at a Goodwill store yesterday was not related to recent bombings, authorities said. Police and emergency response teams said an artillery simulator detonated, injuring a man in his 30s.