Police say the woman is in her 40s, but they haven't released any other information.
"We can not rule out that hate crime is at the core of this but we are not saying that that is the cause", Austin Police Chief Brian Manley told a news conference.
Austin police responded late Monday morning to a report of a second home explosion as authorities continued to investigate an early-morning blast that killed a teen and seriously injured a woman. Police said they have reclassified that investigation as a homicide, and can not rule out that the two explosions aren't related.
Both cases are now being looked at as being related, according to Manley, who says there are similarities of the two incidents.
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However, a motive in the two incidents remains unclear at this time. It happened as thousands of visitors are descending on the city for the South by Southwest music, film and technology festival, and authorities urged residents to call the police if they receive any packages they aren't expecting.
They are also not ruling out the possibility of the explosions being hate crimes due to the fact that both victims were African-American.
In both cases, the packages apparently were delivered overnight and found in the morning, Manley said.
Anthony Stephan House was critically injured in the explosion on his front porch around 6:55 a.m. March 2, on the 1100 block of Haverford Drive, which is about 12 miles away from Oldfort Hill Drive neighborhood.
Manley said all of the agencies are working to gather evidence from the scene so that they can have it analyzed.