A 24-year-old man suspected of a series of deadly bombings that have terrorised the Texan capital of Austin for almost a month has blown himself up as police closed in on him, as the FBI warned that other parcel bombs might have been planted.

The suspect, identified by a law enforcement official as Mark Anthony Conditt, killed himself in his car at the side of a road as authorities moved in to arrest him early on Wednesday, officials said.

Austin Police Chief Brian Manley identified the suspect as a 24-year-old white man. He said a motive for the bombings is not yet known and it is unclear if the man was acting alone or with accomplices.

Mr Manley said the suspect is believed to be responsible for all five bomb explosions that have killed two and wounded several more and put people on edge in the Texan capital since March 2.

But FBI agent Chris Combs, head of the agency's San Antonio office, said: "We are concerned that there may be other packages that are still out there."