Monday, law enforcement and federal investigators were still on scene of an explosion at Oldfort Hill when they were called to another explosion on Galindo Street.
Police said a Hispanic woman in her 70s was critically injured after the package left on her front doorstep detonated.
"Well, it woke me up. I heard a boom and then I heard screaming afterwards," said Diem Delahou who lives a block from the crime scene.
While police are being careful not to call this a serial bomber, they now have a pattern of exploding packages left at homes in East Austin. That's why officers said it's important that anyone who receives a package they were not expecting or one that looks suspicious leaves it where it is and calls 911.
"They said that she opened the door, picked up the package and it just went off and from there the glass went everywhere. It went into her body, into the frame of the house, it just went shooting out," said Brandon Rendon who lives four houses away from where the blast occurred.
The victim was transported to a local hospital with life threatening injuries.
Police are still working to find a link between the victims or a motive in all three explosions, but said evidence at all three scenes leads investigators to believe they are connected.
"We are having innocent people getting hurt across this community and it is important that we come together as a community and solve this," said Austin Police Interim Chief Brian Manley.
Manley said the FBI has two teams working the cases and the ATF has called in their National Response Team to help as well. The National Response Team consists of special agents, explosive specialists, fire investigators, forensic specialists, canine teams and other veteran analysts.
"We will leave no stone unturned because we are not going to allow this to go on in our city," said Manley.
Manley said the packages are not being left by any official mail delivery services. Victims are finding them in front of their home and the device is detonated when the package is being picked up or opened.
"If you receive a suspicious package, a suspicious cardboard package, but, again, really I don't want to limit this to anything. If you receive a suspicious package, then call us and let us come out because a device like this can be hidden in many different ways," said Manley.
Until police find a motive or a link between victims, they're unable to rule out whether those injured or killed were the intended targets.
"It's not time to panic, but it's time to be vigilant and it's time to pay attention. It's time to pull together as a city and a community and solve this," Manley said.
Police said they have been responding to calls about suspicious packages at other homes in the city, but so far none of them have contained any kind of explosive devices.