FBI agents investigate the scene at a FedEx distribution center where a package exploded in Schertz, Texas. Authorities believe the package bomb is linked to the recent string of Austin bombings. Picture: Eric Gay/AP

Austin, Texas - A 24-year-old man suspected of a series of deadly bombings around Austin, Texas, blew himself up early on Wednesday on the side of a highway as police closed in on him, police officials said.

Police had tracked the suspect to a hotel near Austin, the state's capital city, and were following him when he pulled to the side of the road and detonated a device, killing himself, Austin Police Chief Brian Manley told reporters near the scene.

"The suspect is deceased and has significant injuries from a blast that occurred from detonating a bomb inside his vehicle," Manley told reporters. He said the suspect was white, but declined to provide his name.

Two Austin police officers were approaching the vehicle when the suspect set off his device. One officer fired at the vehicle and the other sustained a minor injury when the bomb went off, Manley said.

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Police had urged residents of the area to treat packages with suspicion during the bombing campaign, and Manley warned residents not to let their guard down yet, since investigators were not sure whether the suspect had placed or sent more bombs.

Two people were killed and more injured by a string of bombings in Austin, Texas's capital city, earlier this month.

The bombings began with parcels left on doorsteps, then continued with a bomb apparently set off by a tripwire on Sunday and two packages that detonated at FedEx Corp facilities on Tuesday.