Authorities searching the home of the Austin bomber, who blew himself up in his car Wednesday as police closed in, found a trove of more homemade bombs in his home and evacuated a four-block area to avoid more death or injury.
The explosives were found in the home of Mark Anthony Conditt hours after the 23-year-old man died in a ditch near Round Rock as two SWAT team members advanced on his vehicle.
Authorities said the motive of the attacks remains a mystery. They were also unsure whether Conditt acted alone in making and delivering the five bombs in the Texas capital and suburban San Antonio that killed two people and wounded four others since March 2.
Federal agents who descended on Conditt's frame house in Pflugerville, detained two of his roommates before letting one go.
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Inside, according to a statement by FBI, Bureau of Alcohol, Tobacco, Firearms and Explosives and the Austin police, they found a cache of homemade bombs and cleared an area around the house "in an abundance of caution" as they removed and disposed of the explosive devices.
Authorities also warned residents of the Austin area that Conditt may have also planted or mailed other explosive devices during the last 24 hours. He called the public to be vigilant, despite Conditt's death early Wednesday.
After zeroing in on Conditt as the prime suspect, police in the pre-dawn hours Wednesday located his vehicle outside a hotel in Round Rock, about 20 miles north of Austin. They moved into the area in force, but awaited the arrival of beefed-up tactical teams in hopes of taking Conditt alive.
Instead, Conditt's vehicle began to leave the parking lot, with police in pursuit. When the vehicle went into a ditch, Conditt detonated the explosive device inside as two SWAT team members approached.
One officer was knocked back by the explosion, suffering minor injuries, while a second fired on the suspect, who died of "significant injuries" from the blast, said Austin Police Chief Bryan Manley.
A federal arrest warrant filed Tuesday in federal court accused Conditt, who lived near his parents in the community of Pflugerville north of Austin, of "receiving, possessing or transferring a destructive device." Details of the complaint remained sealed Wednesday.
Surveillance video from a FedEx drop-off location north of San Antonio, where the suspect was allegedly seen entering with a package, captured images of Conditt wearing a blond wig and hat while bringing his packages in for delivery.
Texas Gov. Greg Abbott told reporters that authorities knew Conditt's cell phone number before they knew his name and used information from phone towers to tie the number to the location of the bombings and track his movements.
Abbott also said the suspect bought bomb-making materials at a Home Depot, where he also picked up five signs that read: "Caution, children at play."
Chris Combs, head of the FBI's San Antonio office, said the agency was concerned there may be other packages still out there.
Manley said authorities feared additional devices in the area because they "don't know where the suspect has been the past 24 hours" before they zeroed in on him.
Investigators noted he researched addresses online in Cedar Park and Austin and apparently was aiming to use them as targets, KVUE reported, quoting sources close to the investigation.
Conditt, who was unemployed, attended Austin Community College's Northridge Campus as a business major from 2010 to 2012, but did not graduate. He worked at Crux Semiconductor in Austin, the Austin American-Statesman reported.
In posts written in 2012 for a college course, a blogger identifying himself as Mark Conditt said he enjoyed "cycling, parkour, tennis, reading, and listening to music."
"I am not that politically inclined," he wrote. "I view myself as a conservative, but I don't think I have enough information to defend my stance as well as it should be defended. The reasons I am taking this class is because I want to understand the US government, and I hope that it will help me clarify my stance, and then defend it."
A close high school friend, Jeremiah Jensen, 24, told the American-Statesman that Conditt was a "deep thinker" but a "little rough around the edges."
"He was a very assertive person and would ... end up being kind of dominant and intimidating in conversation," Jensen told the newspaper. "A lot of people didn't understand him and where he was coming from. He really just wanted to tell the truth. What I remember about him he would push back on you if you said something without thinking about it. He loved to think and argue and turn things over and figure out what was really going on."
Conditt and his father, Pat Conditt, bought a house last year in Pflugerville, Texas, where he had been living.
A neighbor, Mark Roessler, said Conditt was a familiar sight in the community and would return his wave from across the street.
The suspect and his father were rehabbing their house, Roessler said. He knew the dad better than the son and described the older Conditt as devoted father and a good man.
Troopers from the Texas Department of Public Safety and agents with the ATF cordoned off several blocks in the neighborhood around the house Wednesday morning.
Fralen Allen, who works nearby, said he was stunned that the quiet community would be a crime scene. "I'm sickened," she said. "Surely in hindsight someone must have known and maybe this could have been prevented."
Officially, Manley declined to identify the suspect, describing him only as a white man. He said officers were tipped to his involvement 36 hours earlier.
Fred Milanowski, agent in charge of the ATF's Houston Field Division, said investigators believe the dead suspect built all four of the package bombs that terrorized Austin since March 2. The explosives killed two people and seriously wounded four others. A fifth parcel bomb detonated at a FedEx distribution center near San Antonio early Tuesday.
NBC News reported a key part of the puzzle was the discovery of an "exotic" and foreign battery in each explosive, which helped authorities tie the bombings together.
Austin Mayor Steve Adler thanked law enforcement for their work in bringing down the suspect and urged residents to continue to report anything that appeared suspicious or out of place.
"We're just really relieved and just incredibly thankful for this army of law enforcement that has been in our community here for the last week or so," he said on NBC's Today show.