Texas has been rocked by a fifth explosion in less than three weeks, placing the state on high alert.
Early on Tuesday morning, a bomb exploded at a FedEx distribution centre near San Antonio, injuring one person.
Police have now sent a hazardous materials team to a FedEx facility in Austin after a report of a suspicious package.
Federal agents say the explosion on Tuesday morning may be linked to other attacks by what they believe is a serial bomber.
This is now the fifth explosion in Texas in less than three weeks – four of which have taken place in the state capital, Austin.
Three package bombs inside cardboard boxes were left on doorsteps over ten days starting on March 2, killing two people and injuring two others.
On Sunday, an explosion triggered by a ‘nearly invisible’ tripwire injured two more people.
Victims had nails in their legs from the explosion but the injuries are reportedly not life threatening.
Police had initially believed the bombings were linked to hate crime but victims have now been from a diverse range of backgrounds.
FBI agent Michelle Lee has said that although it is still early in the investigation, "it would be silly for us not to admit that we suspect it's related".
On Tuesday, the White House said the federal government is doing "whatever is necessary" find who is responsible.
White House Press Secretary Sarah Huckabee has said President Donald Trump is aware of the situation.
Authorities are urging Texans to be cautious when opening packages, and to report anything suspicious.
Timeline of explosions:
2 March: Explosion takes place on the front porch of 39-year-old Anthony Stephan House's home in Austin. He later dies at a hospital nearby.
12 March: A 17-year-old dies and a woman left seriously injured after a package explodes at their home in Austin.
12 March: A second package bombing in the same day leaves a 75-year-old woman in a "critical, but stable condition."
18 March: Two men are injured after an explosion possibly caused by a trip wire.
20 March: A device explodes at a FedEx distribution centre near San Antonio - the only incident outside of Austin.