The man suspected of carrying out a series of linked bombings in Texas has died after blowing up a vehicle as police closed in on him.
The suspect was killed in Round Rock near Austin, the state's capital, after police gave chase at about 3am local time on Wednesday, authorities confirmed.
Officers had tracked the suspect to a hotel and a SWAT team was pursuing him when he pulled to the side of the road and detonated a bomb, killing himself, Austin Police Chief Brian Manley told reporters.
A police officer suffered minor injuries from the blast and a SWAT team member fired a shot at the vehicle.
President Donald Trump hailed the bomber's death in a tweet saying: "AUSTIN BOMBING SUSPECT IS DEAD. Great job by law enforcement and all concerned!"
AUSTIN BOMBING SUSPECT IS DEAD. Great job by law enforcement and all concerned!
— Donald J. Trump (@realDonaldTrump) March 21, 2018
Police Chief Manley identified the suspect only as a 24-year-old white male but the suspect's name will not be released until his next of kin are notified.
Manley said the motive is not yet known, however two of the victims of the bombing spree were black and one was Hispanic, which has previously led to suggestions of a race hate link.
FBI agent Chris Combs, head of the agency's San Antonio office, warned that the danger may not be over as there could still be more bombs planted before the suspect died.
He said: "We are concerned that there may be other packages that are still out there."
— Round Rock Police (@roundrockpolice) March 21, 2018
Local station KVUE News reports that FBI agents and police traced the bomber using mobile phone technology, CCTV and shop receipts before "engaging him".
Officers tracked him to a hotel near Round Rock where they took up positions in a carpark.
As they waited for specialist teams to arrive the suspect drove off, sparking a chase.
Police teams pursued him and when the suspect pulled over, armed police approached to try and arrest him - but he detonated the bomb.
Interstate 35 was closed in the southbound direction with dozens of police vehicles clustering on the highway.
The dramatic close to the terrifying bombing spree came after CBS released images of a suspect delivering packages to a FedEx office on Brodie Lane in the south of Austin.
The pictures showed a man in a cap delivering two parcels at about 7.30pm on Sunday.
Video from the scene showed the huge police response in Round Rock as traffic came to a standstill.
Local media reports that an earlier shooting involving a police officer which was tweeted by Austin Police may also be related to the standoff but it is unclear.
APD is working an Officer Involved Shooting in the 1700 block of N. IH-35. Media staging area will be at the Sherwin Williams Paint, 3321 N. IH-35. APD PIO will be en-route.
— Austin Police Dept (@Austin_Police) March 21, 2018
Police had been seeking a suspect or suspects in a mysterious spree of parcel bombings that has killed two people and injured several more this month.
The series of blasts escalated on Tuesday with two incidents in a single day: a bomb that exploded at a FedEx distribution centre near San Antonio, and one that was discovered before it detonated.
A third explosion on Tuesday evening in Austin was not a package bomb and officials said it did not appear to be related to the other incidents.
Yesterday's bombings brought to six the number of explosive devices - five that detonated - to have come under investigation in Texas this month as the work of a possible serial bomber.
The first explosion took place on March 2 killing a 39-year old man.
A 17-year-old boy was killed and two women were injured in two separate blasts on March 12.
On Sunday, two men - ages 22 and 23 - were injured in a blast trigged by a tripwire.
A worker at a FedEx distribution centre was treated and released on Tuesday morning after the incident there.