'We can not rule out that hate crime is at the core of this but we are not saying that that is the cause, ' Manley told reporters.
Police in the US city of Austin, Texas, said on Monday that they believed that three package bombings over the past 10 days were "related". Monday's first explosion happened 12 miles from the home where the 2 March package bomb killed Anthony Stephan House.
Police had initially deemed House's death "suspicious" - saying it couldn't be ruled out that he had assembled the package himself - but on Monday reclassified his death as a homicide. The early morning bombing killed a 17-year-old boy and sent an adult woman to the hospital with non-life threatening injuries. Later, an explosion put a 75-year-old Hispanic woman in critical condition with "life threatening injuries", Manley said. "There are similarities that we can not rule out that these two items are, in fact, related", Manley said.
A police officer guards the scene of an explosion on Galindo Street in Austin, Texas, on Mon., March 12, 2018.
At 6:55 a.m., police said they were called to a home in the 1100 block of Haverford Drive, near East Howard Lane and Harris Ridge Boulevard, in the Harris Ridge neighborhood.
Mr Manley had earlier tweeted: "My heart goes out to the family of the individual who died and was injured from the explosion in Old Fort Hill".
The package was brought inside the house, and it detonated as it was being opened, police said.
"We are having innocent people getting hurt across this community, and it is important that we come together as a community and solve this", Manley said, later adding, "It's not time to panic". Manley said it's unknown if the victims were intended targets.
Police were processing the scene at the first Monday explosion when the second occurred.
"That case was being investigated as a suspicious death", Manley said today according ABC News, regarding the March 2 incident. However, they cannot say it is the cause.
Police fear a racist package bomber could be on the loose after a second African-American person was killed by an exploding package in two weeks.
On March 2, a man died after a package exploded on the front porch of a home on Haverford Drive. Both attacks are being investigated by local and federal authorities.
His department is working with the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives to determine whether both bombs were similar and to identify the person, or people, who built them.
In all three cases, he said, the packages did not appear to have gone through the Postal Service or private carriers such as UPS but were left on doorsteps without a knock or ringing of doorbells. A woman also was injured in the Monday morning blast. "Until we find who committed this act and take them into custody, it is appropriate for residents to be concerned if you receive a package that you were not expecting, a package that is not marked properly, or is not from someone that you know".