Residents of a home on the eastern edge of Austin rose Monday to find a package that they weren't expecting outside the front door.
In this era of internet shopping, such brown boxes are ubiquitous. So they took it inside to the kitchen. That's when, according to police, it exploded.
Someone had placed a bomb inside. The blast killed a 17-year-old boy and injured a woman.
A few hours later, about five miles south, a 75-year-old woman found a similar package on her porch. When she picked it up, it detonated, sending her to the hospital with life-threatening injuries, officials said.
Investigators quickly realized that the bombings strongly resembled a March 2 case involving a package that exploded and killed a man in his northeast Austin home.
As hundreds of thousands of visitors are swarming Austin for the annual South by Southwest festival, which began Friday and runs through March 17, police said they had linked the three package bombings — raising fears that someone is trying to terrorize the Texas capital during the city's biggest event of the year.
Police have not said the bombings pose a threat to the festival. "The substantial security operation already in place for SXSW has been instructed to be extra vigilant," a festival representative said in a statement.
Police also have not identified a suspect or given a possible motive as federal officials joined the investigation.
"We are not ruling anything out at this point," Police Chief Brian Manley said at a televised news conference. "We're imploring the community, if you know anything about these attacks, it is imperative that you come forward and let us know. We have innocent people getting hurt across this community."
On Monday, authorities reclassified the death of Anthony Stephan House, 39, who was killed in the first package bombing, from suspicious to homicide.
With little information on a possible motive or suspect, officials told residents to be especially wary of any unexpected packages on their doorsteps.
Manley suggested that residents call 911 if they find anything suspicious, and leave their homes or wait in the rear until officials arrive.
"We will respond," Manley said. "It make take a little while to get there because we are getting several calls."
The packages don't appear to have been sent through traditional delivery services such as the U.S. Postal Service or United Parcel Service and were left without ringing the bell, said Manley, who declined to give details about the explosive devices but suggested they came in cardboard boxes.
"These devices can explode in many ways, either by being moved or being opened," Manley said, also cautioning that the bombs "can be hidden in many different ways.… There is a certain level of skill required to put a device like this together successfully."
Austin investigators are being assisted by the FBI, the Bureau of Alcohol, Tobacco, Firearms and Explosives, and the Postal Service.
Rick Hahn, a retired FBI special agent and counter-terrorism consultant, said investigators would probably take a close look at the components used in each bomb to see whether any unique parts can be traced back to a seller or manufacturer, which might lead authorities to the killer or killers.
"There's oftentimes unique factors amongst the components that will narrow down distribution, sales point, that sort of thing," Hahn said. If the bomb used particular types of wires or batteries, "all that becomes investigative leads for us to track down."
The victims of the first two bombings were black, raising fears early Monday that they had been targeted because of their race. But the next victim was a Latina, after which police declined to speculate on a possible pattern.
"We have no specific ideology or victimology behind this, and it will remain an ongoing investigation while we pursue any and every lead," Manley said.
"We do not know yet whether the victims are the intended targets," he said, adding that some homes had multiple residents and the bomber may have also targeted the wrong addresses.
The Oldfort Hill Drive bomb attack, where the teenager was killed, occurred less than a mile from several churches.
Lamont Tucker, a longtime resident of the neighborhood who knew the woman injured in the explosion, heard the blast in the early morning.
"I heard the bang, but I didn't think much of it, because somewhere around here they have a shooting range, so I hear gunshots all the time," Tucker said.
He said his "heart is breaking" for the 17-year-old victim, and that "we're going to have to be cautious and watch our surroundings, because people are getting outrageous."
The second blast Monday occurred on Galindo Street, a compact residential area filled with families and children.
A perimeter was set up, with residents going in and out of restricted streets cordoned off by police tape.
A woman who gave her name only as Ruby said she lives on the street behind Galindo and was home with her mother at the time of the blast.
"We heard this loud noise," Ruby, 18, said. "It was a loud bang, like something hitting something else."
She said residents were on high alert — made nervous even by packages addressed to them.
"My mom was scared to pick up the mail," Ruby said.
Pearce reported from Los Angeles and Yamato from Austin.
8:15 p.m.: The story was updated with additional details and reaction.
2:17 p.m.: The story was updated with reports of a third bombing and additional details.