The man believed to be responsible for a three-week bombing campaign in Texas that killed two people and injured five others has been identified after he blew himself up in a dramatic standoff with police.

Austin police chief Brian Manley said police tracked the suspect to a hotel about 32 kilometres north of Austin and followed him when he pulled to the side of the road and detonated a device, killing himself.

The man was identified as an unemployed 23-year-old Mark Anthony Conditt, of Pflugerville, Texas.

Mr Manley said Conditt set off a bomb as two Austin police officers approached the vehicle.

“The suspect is deceased and has significant injuries from a blast that occurred from detonating a bomb inside his vehicle,” he told reporters.

Police say Conditt took his own life by detonating a bomb. Photo: Facebook

One officer fired at the vehicle and the other sustained a minor injury when the bomb went off, Mr Manley said.

Investigators had tracked Conditt for several days before closing in at the unidentified hotel, not far from his home in Pflugerville.

Police are now scrambling to determine whether more explosives remain in the city.

“We don’t know where this suspect has spent his last 24 hours, and therefore we still need to remain vigilant to ensure that no other packages or devices have been left throughout the community,” Mr Manley said.

Authorities later recovered homemade explosives from inside the home Conditt shared with two other men.

The Austin Police Department and federal authorities said in a statement Wednesday afternoon that they were “working to safely remove and dispose of” the explosives at the home.

Authorities evacuated four blocks around the building “in an abundance of caution”.

Police earlier detained two people who lived with Conditt.

Austin police said Wednesday that one roommate was questioned and later released, while the second was still being held for questioning.

Authorities did not release the names of the roommates, explaining that they had not been placed under arrest.

Conditt’s family said it is “devastated and broken” at the news of his alleged crimes.

The Conditt family released a statement expressing shock and grief, as well as offering “prayers for those families who have lost loved ones … and for the soul of our Mark”.

Conditt attended Austin Community College (ACC) before dropping out before graduation in 2012.

According to a Facebook post by Conditt’s mother, reviewed by TIME magazine before it was deleted, he was homeschooled until 2013 and was planning a possible religious missionary trip.

Conditt also created a blog about his political views as a requirement for a political-science class he took at ACC, detailing views against gay marriage, on “free abortion” and sex offender registration stances, as well as an argument for the death penalty.

“Homosexuality is not natural. Just look at the male and female bodies. They are obviously designed to couple,” he wrote in one of the posts.

In the blog’s biography, he described himself as a conservative who enjoyed cycling, parkour, tennis, reading and listening to music.

Conditt was the oldest of four children and reportedly worked at a manufacturing company, but was dismissed last August because he wasn’t meeting expectations.

The chairman of the US House Homeland Security committee said authorities believed Conditt had “above average intelligence.”

Republican Congressman Michael McCaul told the AP that the suspect matched the FBI’s initial profile suspicion that the bomber was likely a white male. But he says a psychological profile probably won’t be known until investigators go through Mark Conditt’s writings and social media postings.

Mr Abbott added it was “hard to say” if the bombing suspect had acted alone.

Surveillance footage released to local media showed Conditt taking packages to be shipped and attracting notice because of a seemingly obvious disguise – a light-coloured wig and gloves.

BREAKING: Exclusive photos of Austin bombing 'Person of Interest' dropping off 2 packages at Austin @FedEx store. Believed to be wearing wig.
Recognize him? Contact: @FBI @Austin_Police
More info: https://t.co/8bVRGToc7T @News4SA @cbsaustin pic.twitter.com/mpTxxrkYfd

— Randy Beamer (@randybeamer) March 21, 2018

Texas Governor Greg Abbott told Fox News authorities knew the likely identity for the bomber for several days.

“Law enforcement is at his house in Pflugerville where we are learning whether or not that was the location he was making his bombs,” Mr Abbott said.

“He did not have a criminal record as best we can tell, so there seems to be very little information about him,” he said.

Mr Manley said the Conditt was believed to be responsible for six bombs around Austin, all but one of which detonated.

He said the motivation for the bombings or whether the suspect had help was not yet known.

Austin police chief Brian Manley says police are investigating the motive behind the bombings. Photo: AAP

Mr Manley warned residents to be cautious since it is not clear whether any more bombs have been left around the city.

While officers waited for SWAT reinforcements before arresting him, the suspect left the hotel and police followed.

The suspect pulled off the city’s main highway and the two Austin police officers approached his vehicle when he set off his device.

US President Donald Trump congratulated authorities on Twitter: “Great job by law enforcement and all concerned!”

-with agencies