Police are on high alert in Austin, Texas, after a string of package deliveries have left at least two people dead and several others injured after explosions rocked their homes.
The first explosion unfolded on March 2, killing 39-year-old Anthony Stephan House after a "device" exploded on the front porch of his Austin home. The blast was investigated initially as a suspicious death, and later as a homicide.
Ten days later, a similar incident was reported just 12 miles from House's home. A 17-year-old, identified as Draylen Mason, was killed and his mother was injured after a package exploded inside their home.
Hours after the second explosion occurred, police reported a third blast, confirming that at least one elderly woman was injured.
Austin Police Chief Brian Manley announced at a March 18 news conference that the department, the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) were offering $100,000 — up from the previous reward of $50,000 — for anyone who could provide information leading to an arrest in the case.
The six-figure reward was in addition to a separate reward of $15,000 provided by Texas Gov. Greg Abbott's office.
Manley said investigators now believe the package bombings — which officials previously said were believed to be racially charged — "were meant to send a message."
The police chief said "we want to listen to" whomever was behind the bombings, in order to "understand what brought you to this point."
The explosions were believed to be linked, according to investigators, and officials said they were not ruling out any possible motives — including a possible hate crime, considering all victims are black or Hispanic. Two of the three families affected reportedly knew each other through activism in the local black community.
Here's a timeline of the deadly package explosions shaking Austin -- and what police are advising residents as they continue to investigate the three incidents.
Austin Police received a call about an explosion in a neighborhood on the northwest side of the city after a 17-year-old resident found a package on the front step, brought it inside and opened it in the kitchen, where it exploded.
Authorities confirm a teenager is dead and a woman in her 40s is seriously injured after a package explodes at a home in Austin, marking the second such explosion in the city within two weeks.
Police say the teen died at the scene, while the woman was taken to a hospital with life-threatening injuries.
The FBI offers to assist Austin police with the investigation.
The Austin Police Department holds a press briefing in the neighborhood where the second package bombing occurred.
Authorities say they believe the package bomb that killed the teenager and wounded the woman is linked to the deadly package sent to House's home earlier this month because they were both left on the front doorstep and not delivered by a mail service.
Manley said the U.S. Postal Service does not have a record of delivering a package to the Austin home where the explosion occurred Monday.
Police reclassify House's death as a "homicide investigation," instead of a "suspicious death," as the two incidents may be related.
Manley says investigators hope to collect surveillance video and evidence from nearby homes to identify a suspect.
"We're doing a canvas of the neighborhood right now," Manley says.
Another explosion is reported in the Montopolis neighborhood, located southeast of downtown Austin.
The Austin Police Department confirms police are reponding to an "urgent" call.
Austin-Travis County EMS officials declare a "trauma alert," announcing they are transporting at least one patient to the hospital following a reported explosion.
Austin-Travis County EMS confirm in a tweet that a woman in her 70s has "serious, potentially life-threatening" injuries. A second woman from that address had an unrelated medical issue and was not taken to the hospital.
Police hold another press briefing to update reporters on a third blast in Austin.
Police identify the victim of the third bombing as a 75-year-old Hispanic woman, who is currently in "critical, but stable condition."
Based on evidence gathered at the scene, police say they believe the third incident is related to the two previous ones involving package bombs.
"We do not have a specific victimology ... at this point, we are willing to investigate any avenue that may be involved behind these attacks," Manley says.
Manley says it's not yet clear whether these victims were "intended targets," but asks the community to be vigilant.
"We are having innocent people getting hurt across the community," he adds.
Austin police receive reports of an explosion and find a critically-injured House. The 39-year-old victim is then transported to nearby Round Rock Hospital.
House is declared dead at the hospital nearly an hour later. Authorities announce House's death is being investigated as "suspicious."
The Austin Police Department holds a press conference in House's neighborhood.
Austin police say they've determined the device was inside a package, and are working with the Bureau of Alcohol, Tobacco, Firearms and Explosives to reconstruct the item and learn who may have created it.
“Right now, we're trying to determine how did the package get there and who was the intended target? We do feel that this was targeted at somebody. We're still trying to figure out whether that was the individual who died or not,” Assistant Chief Joseph Chacon with the Austin Police Department tells reporters at a news conference.
Police say it is "an isolated incident and that there is no continuing threat to the community," adding that there is no reason to believe it is terror-related.
“Anytime we have a bomb go off like that and somebody dies, the first thing people think is terrorism. While we cannot completely rule it out at this point, we do not believe that terrorism is a motive in this death,” said Chacon.
House had also faced previous charges in Travis County, according to Fox 7.
Police warn residents to beware of suspicious packages
The package explosives involved in the three incidents were not delivered by the U.S. Postal Service or any private carrier, but were left overnight on doorsteps. Federal law enforcement officials told Fox News the packages were made to look like mail.
More than 500 law enforcement officials have investigated more than 400 possible leads in the case, Manley said March 18.
Police warned residents who found any suspicious packages to call 911, and to send tips to Austin Crime Stoppers at (512) 472-8477 or Texas Crime Stoppers at 1-800-252-8477.
Fox News' Nicole Darrah and Travis Fedschun and The Associated Press contributed to this report.