Two package bomb blasts a few miles apart killed a teenager and wounded two women in Austin on Monday, less than two weeks after a similar attack left a man dead in another part of the city.

The first of Monday's attacks killed a 17-year-old boy and wounded a 40-year-old woman, both of them black. As Police Chief Brian Manley held a news conference to discuss that blast, authorities were called to the scene of another explosion that injured a 75-year-old Hispanic woman. She was taken to a hospital with potentially life-threatening wounds.

Authorities suspect that both of Monday's blasts were linked to a March 2 attack that killed a 39-year-old black man, and they urged the public to call police if they receive any unexpected packages.

"This is the third in what we believe to be related incidents over the past 10 days," Manley said while briefing reporters near the site of Monday's second explosion. He at first suggested that the blasts could constitute a hate crime, but later amended that to say authorities had not settled on a motive and could not rule anything out.

"We are not ruling anything out at this point," said Manley, who said the intended targets were not clear since multiple people live in the homes where explosives were placed. "We are willing to investigate any avenue that may be involved."

The police chief refused to provide many details about the explosives, citing the ongoing investigation. But he said they were an "average size letter box" and "not particularly large." In all three cases, he said, the packages did not appear to have gone through the U.S. Postal Service or private carriers like UPS but were left on doorsteps without a knock or ringing of doorbells.

The explosions happened far from the main events of the wildly popular festival known as SXSW, which brings about 400,000 visitors to Austin each year. The police chief urged visitors to "be aware of what's going on."

"Enjoy yourself. Have a good time," he said. "There's no reason to believe that you are at any greater risk other than be aware, look for things that are suspicious."

In a tweet, organizers said, "SXSW is heartbroken by the explosions in Austin," and they urged visitors to stay safe and alert police if they see any suspicious activity.

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 three explosions occurred in different parts of east Austin. Monday's first blast happened at a home in Springdale Hills, a leafy neighborhood of houses mostly from the 1960s and 1970s. After the attack, officials in hazardous materials suits came and went regularly.

That was about 12 miles (20 kilometers) from the home where the March 2 package bomb killed 39-year-old Anthony Stephan House. House's death was initially investigated as suspicious but is now viewed as a homicide.

The day's second explosion occurred around the Montopolis neighborhood, about 5 miles south of the day's first blast.

A neighbor who was home at the time of Monday's second bombing initially thought it sounded like a gas pipeline explosion.

Brandon Rendon said he's lived in the neighborhood for 27 years and couldn't believe this happened so close to home.

"It's unreal," he said. "For an explosion to go off like that — it could have been anybody. A kid, or anybody, so it's just...it's just very scary."

Joanna Samarripa, who lives around the corner, said she saw a woman slumped in the doorway of the home after rushing over moments after the explosion.

"The cops were running and telling everyone 'Get out of the house! Get out of the house!'" Samarripa said. "I'm still scared. I'm still shaking. I don't even want to leave my daughter no more."

Neighbor Keith Reynolds heard what sounded to him like a propane explosion. He rushed outside and saw a cloud of hazy smoke and others on his street running to help.

"There was a horrible screaming. You knew that something terrible was happening," Reynolds said, adding that the victim's body was riddled with holes as emergency responders took her out of the house and into an ambulance.

"It's just a regular family neighborhood," he said. "It's just a grandmother, you know what I mean? Like, why?"

FBI teams from Austin, San Antonio and Dallas were investigating as was the Bureau of Alcohol, Tobacco, Firearms and Explosives. Manley said anyone receiving a package they were not expecting should call 911.

"Under no circumstances should you touch them, move them or handle them in any way," he said.

The victims in Monday's blasts were not immediately identified.

Texas Gov. Greg Abbott said his office's criminal justice division is offering a reward of up to $15,000 for "information leading to the indentification and arrest of the person or persons involved in the deadly package blasts that have occurred in Ausitn over the past 10 days."

Anyone with information should submit tips to Texas Crime Stoppers using one of the following methods:

Call the hotline at 800-252-TIPS (8477)

Text the letters "DPS" followed by your tip to 274637 (CRIMES)

Submit a tip through the website

Submit a tip through the DPS mobile app

Associated Press writer David Warren in Dallas contributed to this report.