AUSTIN, Texas -- Police in Austin say "similarities" between three package explosions in Texas' capital city this month, two fatal, lead them to believe the incidents are related. The latest fatal incident, reported Monday morning, killed a 17-year-old boy and wounded a woman, Austin police chief Brian Manley said.

The boy died at the scene and the woman in her 40s was taken to the hospital with potentially life threatening injuries after the explosion at the East Austin home before 7 a.m. In an earlier incident March 2, Anthony Stephan House, 39, was killed when a package exploded at his northeast Austin home, CBS affiliate KEYE-TV reports.

Police also responded around 11:50 a.m. Monday to the report of an explosion in southeast Austin in which a woman was badly injured. Police received multiple calls about an explosion, Manley said at a press conference Monday afternoon. The victim in the incident came outside of her home to retrieve a package left on her front step, which exploded.

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She is a 75-year-old woman and is listed in critical but stable condition, Manley said. Her injuries are considered life threatening.

"This is the third in what we believe to be related incidents," Manley said.

Manley said a task force had been formed to investigate the incidents. He urged residents to be careful and not to open suspicious packages. If residents encounter any packages left at their homes they aren't expecting, he urged them to call 911.

"It's not time to panic, but it's time to be vigilant and it's time to pay attention, it's time to come together as a city and solve this," Manley said.

The scene of a deadly package explosion in Austin, Texas, on Mon., March 12, 2018. KEYE-TV

In the two previous fatal incidents, the packages were also left at the doorstep of the home apparently in the overnight hours and opened by the resident in the early morning hours, Manley said. All three of the packages were apparently left at the doorstep and were not delivered through the postal service or another carrier service, according to Manley.

The three explosions occurred in different parts of Austin. Monday's first explosion happened at a home near the city's Windsor Park neighborhood and about 12 miles from the home where the March 2 package bomb killed 39-year-old Anthony Stephan House. His death was initially investigated as suspicious but is now viewed as a homicide.

Monday's second explosion happened in the Montopolis neighborhood, near the airport and about 5 miles south of the day's first blast.

My heart goes out to the family of the individual who died & was injured from the explosion on Old Fort Hill Dr. This type of crime will not be tolerated in #ATX. If you receive a package that you are not expecting or looks suspicious, DO NOT open it, call 911 immediately. pic.twitter.com/sJSYQZMziv — Chief Brian Manley (@chief_manley) March 12, 2018

Speaking before the third incident, Manley said investigators aren't sure of a motive, but can't rule out the possibility of hate crimes because the residents of both homes were African-American. He now says they aren't ruling anything out, but they are no longer "making the connection to a hate crime."

The victim in the latest incident is Hispanic, Manley said.

Bomb-sniffing dogs were reportedly at the scene of the explosion Monday morning and nearby homes were evacuated. Police initially were concerned about a second package at the home, but have since cleared it and believe it to be unrelated, Manley said.

The explosions happened with hundreds of thousands of visitors in the city for the South by Southwest music, film and technology festival. The explosions happened far from the festival's main events, but organizers are urging those visiting Austin, "if you see something, say something." Police said festivalgoers weren't at risk but should be aware of what's happening.

In a tweet Monday, organizers said, "SXSW is heartbroken by the explosions in Austin" and asked the thousands of festival attendees to notify the authorities of anything suspicious.

SXSW is heartbroken by the explosions in Austin earlier this month and today. Our thoughts are with the victims and those affected. @Austin_Police are conducting ongoing investigations related to these incidents. Please stay safe, and if you see something, say something. https://t.co/ptMu3fylec — SXSW (@sxsw) March 12, 2018

Four years ago, a driver plowed through a barricade and into festival-goers, killing four people and injuring many others. Additional security measures were taken in the aftermath, including additional policing, tougher security checks and brighter street lighting, among others.

The FBI is helping Austin police in the package bomb investigation. The ATF was also responding to assist. Authorities are searching nearby homes for any external video cameras that may be able to offer clues.

Fifteen-year-old Isaiah Guerrero, who lives on the street behind where the most recent blast occurred, says the explosion shook him and his house. He says, "You don't hear that stuff in my neighborhood."

The Texas governor's office is offering a reward of up to $15,000 for information leading to the arrest of those involved in the deadly package blasts. In a statement, Gov. Greg Abbott said he's been briefed by the Texas Department of Public Safety on the situation. He also says he's offered the Austin Police Department whatever assistance it needs in its investigation.

To be eligible for the reward, tips must be submitted to Texas Crime Stoppers by telephone to 1-800-252-TIPS (8477), by texting "DPS" and the tip to 274637 (CRIMES), by using the Texas Crime Stoppers website, or by using the DPS mobile app.

Abbott says he wants to assure Texans, especially those in the Austin area, "that local, state and federal law enforcement officials are working diligently to find those responsible for these heinous crimes."