The serial bomber that has terrorised Austin, Texas has blown himself up as police closed in on him.

Austin Police Department chief Brian Manley said it had been a long three weeks for the community of Austin as bombs had been placed throughout the community.

He said in the past "24 to 36 hours" there had been information on one person of interest.

As investigations continued that person moved to be a suspect.

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Last night they felt confident the suspect, a 24-year-old white male, was responsible for the bombing incidents in Austin.

Police managed to track down the vehicle believed to be driven by the suspect to a hotel in Round Rock and ATF and FBI staff surrounded the building as they waited for a tactical unit to arrive, he said.

"We wanted to have ballistic vehicles here so we could attempt to take this suspect into custody as safely as possible."

The vehicle started to drive away before the unit arrived so police followed as they waited for the tactical unit.

The vehicle stopped soon after in a ditch, members of the Austin police SWAT team approached the vehicle, then the suspect detonated a bomb inside the vehicle and knocked a officer back.

Another officer then fired at the suspect.

The suspect is dead and had significant injuries from the bomb detonation.

The bomber could not yet be named because he had not yet been identified by a medical examiner and next of kin had not been identified, Manley said.

The news comes after the Austin police department said on Twitter that there had been an "officer-involved shooting" about 20 kilometres north of the city centre.

Austin authorities have been on high alert since a series of recent parcel bombs in the area killed two people.

The offender's death came just hours after CBS News obtained the first pictures of him dropping off two suspicious packages at a FedEx facility on Sunday.

In the latest serious incident, a woman was injured at a FedEx sorting centre near San Antonio, according to CBS Austin.

The exploding package contained nails and shrapnel and was destined for an address in Austin.

Another parcel which was later found at a second location.

The FBI confirmed the "suspicious package" contained an explosive device, WFMY News 2 reported.

The second package was discovered at a sorting facility near the Austin airport.

A FedEx spokesman said: "The individual responsible also shipped a second package that has now been secured and turned over to law enforcement."

The suspect carried out a 19-day period of fear across Austin by leaving behind explosive packages.

CNN reported the turning point that allowed police to narrow in on the suspect was possibly when an explosive package was sent through Fedex.

-news.com.au