PFLUGERVILLE, Texas (AP) — As a SWAT team closed in, the suspected bomber whose deadly explosives terrorized Austin for three weeks used one of his devices to blow himself up. But police warned that he could have planted more bombs before his death, and they cautioned the city to stay on guard.

Mark Anthony Conditt, an unemployed 23-year-old college dropout, had been tracked down using store surveillance video, cellphone signals and witness accounts of a strange-looking customer making purchases while wearing a disguise that included a blonde wig and gloves.

Police finally found him at a hotel in a suburb just north of Austin known as the scene for filming portions of “Friday Night Lights.” There, officers prepared to move in for an arrest early Wednesday. When the suspect’s sport utility vehicle began to drive away, authorities followed.

Conditt ran into a ditch on the side of the road, and SWAT officers approached. That’s when he detonated a bomb inside the vehicle, Austin Police Chief Brian Manley said.

His motive remained a mystery, and authorities did not immediately say whether he acted alone in the five bombings in the Texas capital and suburban San Antonio that killed two people and wounded four others.

Investigators released few details about Conditt, except his age and that he was white. Neighbors say he was home schooled. He later attended Austin Community College from 2010 to 2012, according to a college spokeswoman, but he did not graduate.

In posts dated from 2012, a blogger who identified himself as Mark Conditt of suburban Pflugerville wrote that gay marriage should be illegal. He also called for the elimination of sex offender registrations and argued in favor of the death penalty. He listed his interests as cycling, tennis and listening to music.

Of gay marriage, Conditt wrote: “Homosexuality is not natural. Just look at the male and female bodies. They are obviously designed to couple.”

Jay Schulze, who lives in Pflugerville, said he was jogging Tuesday night when he was stopped by police and asked about the bombings. He said police flew drones over a home where Conditt lived with roommates for about six hours between Tuesday evening and early Wednesday morning.

He described the home as “a weird house with a lot of people coming and going” and a bit rundown.

A neighbor who watched Conditt grow up said he “always seemed like he was smart” and “polite.” Jeff Reeb said he has lived next to Conditt’s parents for about 17 years and described them as good neighbors. Conditt had visited his parents regularly, he said.

Austin was hit with four bombings starting on March 2. First packages left on doorsteps exploded, then a bomb with a tripwire was placed near a public trail. A fifth parcel bomb detonated early Tuesday at a FedEx distribution center near San Antonio.

Rep. Michael McCaul, a Republican from Austin, said Conditt’s “fatal mistake” was walking into a FedEx store to mail a package because that allowed authorities to obtain surveillance video that showed him and his vehicle, along with his license plate number. From there, McCaul told Austin television station KXAN, investigators could identify the suspect and eventually track him using his cellphone.