HOUSTON -- 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."

Two separate explosions occurred Monday in Austin, capital of the state of Texas, killing a teenager and wounding two women.

According to local police, a bomb detonated in Austin early Monday morning after a teenager brought a package left on the front porch into the kitchen and opened it. The explosion killed the 17-year-old boy and injured a woman in her 40s.

Another blast occurred about five hours later at a home about 8 km southeast of the first explosion. Emergency personnel said they transported a female in her 70s to a medical center with potentially life threatening injuries.

It was the third such incident this month in Austin. A package blast rocked another Austin home on March 2, killing a man.

Austin Police Chief Brian Manley said Monday all three explosions seemed to be "related" but they were not ruling anything out in the investigation.

Of the three explosions, two of them happened in the early morning hours. Both packages were left on the front doorstep and were not delivered by a US mail service, police said.

"We are looking at these incidents as being related based on similarities that we have seen in the initial evidence that we have on hand here today, compared to what we found on the scene of the explosion that took place a week back," Brian Manley said at a news conference.