By Tina Burnside and Joe Sterling CNN
(CNN) — [Breaking news update, posted at 4:00 p.m. ET]
A third explosion in which a package exploded at a residence appears to be connected to two other explosions in Austin, Texas, city Police Chief Brian Manley said Monday at a news conference. A 75-year-old woman was critically injured Monday and a 17-year-old male was injured in an earlier Monday blast. A March 2 blast killed a 39-year-old man.
[Previous update posted at 3:43 p.m. ET]
A pair of package explosions that left two people dead in Austin, Texas, over the past 10 days share similarities and authorities said they suspect they’re connected.
The latest incident occurred Monday morning; the other on the morning of March 2. In both instances, a resident retrieved a package that blew up when it was opened.
Both packages were not delivered via any mail services and both homes are those of African-Americans.
A 17-year-old boy died Monday and a woman was transported with non-life-threatening injuries. Anthony Stephan House, 39, died from injuries in the March 2 explosion, police said.
Authorities are looking into whether the incidents could be hate crimes, but as of now there is no evidence the victims were targeted because of their race, Austin Police Chief Brian Manley said.
"Both of the homes that were the recipients of these packages belong to African-Americans," the chief said at a news conference. "So we cannot rule out that hate crime is at the core of this. But we’re not saying that’s the cause as well."
Both cases are now being investigated as homicides, Manley said.
Police were responding to another "reported explosion" Monday afternoon, but have not yet said whether it is connected to this investigation. In a tweet, Manley strongly urged residents to be on the lookout for suspicious packages and to alert authorities immediately.
"If you’ve received a package that has been left on your doorstep or left in your yard or left on your driveway that you were not expecting or that was not from someone you know, then give us a call," Manley said.
Texas Attorney General Ken Paxton urged all Texans to be cautious. "With three reported explosions in the Austin area, I want to urge all Texans to report any suspicious or unexpected packages arriving by mail to local law enforcement authorities. Call 911 immediately if you receive something suspicious," he said on Twitter.
Local police, as well as agencies including the FBI, and the Bureau of Alcohol, Tobacco, Firearms and Explosives, are working on the case.
The ATF is processing evidence from the first device at its lab and evidence from the second device will also be sent to an ATF lab for consistency.
The annual South by Southwest Interactive Festival began Friday in downtown Austin and ends Tuesday. The explosions are not in the immediate vicinity of the festival.
CNN law enforcement analyst Josh Campbell and CNN’s David Shortell contributed to this report.