"We are looking at these incidents as being related based on similarities that we have seen and the initial evidence that we have on hand here", said Austin Interim Police Chief Brian Manley during the Monday morning press release.
Manley said that while investigators are still searching for a motive, the incidents are under investigation as possible hate crimes because the victims in both cases are African-American. According to CBS Austin, the Federal Bureau of Investigation and ATF are working together on the case.
"We are not going to tolerate this in Austin", Manley said while briefing reporters on the explosion. "Every stop will be pulled out".
Governor Greg Abbott announced a $15,000 reward was being offered for information leading to the identification and arrest of the person or persons involved in the deadly package blasts.
The latest incident occurred Monday morning; the other on March 2. That case was originally being investigated as a suspicious death but has now been reclassified as a homicide investigation.
The first call Monday came at 6:44 a.m.
The 17-year-old found a package outside his house in a tree-lined, mixed race residential area and brought it into the kitchen, where it exploded, Manley said. Neighbors called police after hearing an explosion inside the house. "There is a certain level of skill that is required to put a device like this together successfully and then to have it detonate in the manner in which these are and cause the significant injuries and death that they have", said Manley.
Austin police reported that the explosion that killed House was at about 6:55 a.m. March 2.
Just hours later, police responded to a second explosion miles away from the location of the first explosion where first responders found a 75-year-old woman in critical condition. The package exploded when she picked it up, Chief Manley said. He said his office has not ruled out terrorism. "We are looking at anything that might tie these two together, but again, there are similarities that we can not rule out that these two incidents are in fact related".
Police said people can call 911 if they believe they have received a suspicious or unexpected package left at their homes.
It is not clear whether or not the victims were the intended recipients of the explosive packages, but earlier Monday, prior to the third explosion, Manley said he is not limiting the scope of the investigation.
The U.S Postal Service, FedEx and UPS do not have any records of delivering the packages.
Authorities had said they believe the first two explosions are linked.
He said the timing of the attacks is complicated by the fact that the city is hosting the SXSW conference, with business, music, film and technology leaders spread out at events throughout the city. "Enjoy yourself, have a good time", he said.