'Serial bomber' blamed in Austin explosions after 4th blast rocks city

Show Caption Hide Caption A fourth explosion could be linked to Austin bombings Two men were hospitalized with non-life-threatening injuries after another explosion rocked residents in southwest Austin.

AUSTIN — An explosion that seriously wounded two men and rocked a quiet southwest neighborhood appears connected to a string of mysterious and sometimes deadly blasts this month that have fueled fear across the Texas capital, authorities said Monday.

“Clearly, we are dealing with a serial bomber,” Police Chief Brian Manley said.

Manley said a bomb placed alongside a fence had tripwire the men triggered with their bikes Sunday night. The use of a tripwire, he said, reflects a "higher level of sophistication" than the technology used in the earlier bombings.

Manley said the men suffered "significant" injuries. He said a sweep indicated the area was safe, but he urged residents within a half-mile of the blast site to remain indoors until 2 p.m. local time.

The chief also said 500 law enforcement officials involved in the case at the local, state and federal levels have found “persons of interest,” but no clear suspects have emerged. Authorities asked residents to share home-security video for clues.

Austin resident Leith El-Hassan, 42, said he initially mistook the explosion for thunder.

"We don’t know what’s next," he said. "They have no suspect. It’s just sad that someone is so angry they do this random stuff.”

Nearby resident Richard Herrington, 75, said he heard the blast and immediately knew it was a bomb.

“My initial emotional reaction was, ‘Oh my goodness, I walked my granddaughters right by there,’” he said, adding that he was encouraged by the law enforcement response. "At this point we’re probably in the safest neighborhood you can possibly be in."

The previous three blasts involved suspicious packages left on doorsteps. Manley said the latest bomb, near a road and including tripwire technology, "changes things."

Authorities previously warned residents not to handle unidentified or suspicious packages left at their homes. Now residents must have an "extra level of vigilance" to stay clear of any questionable package — and call 911.

"Our safety message to this point has been ... do not handle packages, do not pick up packages, do not disturb packages," Manley said. "We now need the community to have an extra level of vigilance and pay attention to any suspicious device — whether it be a package, a bag, a backpack — anything that looks out of place. Do not approach it."

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Hours before the blast, Manley had pleaded publicly for the bomber to turn himself in. After the blast, scores of law enforcement officers, including FBI agents, flooded the neighborhood of single-family brick homes to investigate.

Texas Gov. Greg Abbott announced the state is committing $265,000 to the effort to solve the bombings.

“I want to ensure everyone in the Austin region and the entire state that Texas is committed to providing every resource necessary to make sure these crimes are solved as quickly as possible,” Abbott said. “I offer my sincere thanks to law enforcement at the local, state and federal level for their efforts to ensure that those responsible for these attacks are apprehended and brought to justice.”

Frederick Milanowski, ATF special agent in charge, said the tripwire was similar to fishing wire and would have been difficult to see at the time of detonation. Investigators were studying the components of the bomb and injuries to the victims to learn more about the explosives, he said.

The bombs may be different, but the bombmaker is the same, he said.

“We have a high degree of confidence the same individual built all these devices,” he said.

Milanowski said the trip wire used in the explosive was strung near a trailhead and anchored with a metal yard sign, believed to have been brought by the bomb-maker.

Bomb-makers usually build the same explosive over and over, once they have a working prototype, to cut down chances of an accidental detonation, Milanowski said. What makes Sunday’s incident concerning is that the explosive strayed from previous devices, was more sophisticated and was more random, rather than targeted, as the previous three bombs appear to be, he said.

“The really concerning part is that it was so random,” Milanowski said.

Bomb components have been shipped to the ATF national laboratory in Beltstville, MD., where technicians are running chemical, fingerprint and DNA analysis on the components and shrapnel, he said. Meanwhile, more than 500 local, state and federal agents have combed through 400 tips and more than 500 leads, Milanowski said.

“There’s more state and federal resources on this investigation than any investigation Austin has ever seen,” he said, adding: “There’s a lot of information out there. There will be no rock left unturned.”

Two people were killed and two wounded in the earlier attacks. Each had been similar: A plain cardboard box with standard shipping labels was left on a doorstep. Each package had a bomb inside.

Police initially raised the possibility of a hate crime because victims in the first two explosions were black. The third apparent target was Hispanic. The victims of Sunday's blast were white, Manley said. And the first three attacks, unlike the attack Sunday, took place in the eastern part of the city.

Christopher Combs, an FBI agent stationed in San Antonio who was sent to Austin to assist in the investigation, said the varying locations of the four attacks means surrounding communities should also be on guard.

Security analyst Fred Burton of Austin-based Stratfor Worldview, an international security consulting firm, said it was too soon to rule in or rule out international terrorism based on the neighborhoods targeted.

“Is it terrorism? We don’t know yet,” Burton said. “But we do know that he is terrorizing Austin."

Burton said the latest attack indicates the bomber was trying to “stay one step ahead of APD and the ATF.”

The blast occurred on the final day of the popular South By Southwest festival, which attracts global leaders in business, technology, music and film. Authorities said investigators believe the bomber might be sending a message — but they don't know what it is.

“I think we’re looking at a pretty good bombmaker — because all four devices worked,” Burton said. “What we learned from this is that in all probability, this is somebody with military EOD (explosive ordnance disposal) training. I think he’s above average intellect.”

A reward for information leading to an arrest in the case increased to $100,000 from $50,000. That, along with an award from the governor's office, brings the total reward to $115,000.

“There’s more state and federal resources on this investigation than any investigation Austin has ever seen,” Milanowksi said. “There’s a lot of information out there. There will be no rock left unturned.”

Bacon reported from McLean, Va. Contributing: Christal Hayes