AUSTIN, Texas (AP) — Authorities say a package that exploded inside of an Austin home on Monday, killing a teenager and wounding a woman, is believed to be linked to a deadly package sent to another home in Texas’ capital city earlier this month.

Austin police Chief Brian Manley said at a news conference that investigators believe the attacks are linked because in each case, the package bombs were left on the victims’ front doorsteps and not delivered by a mail service. He said the U.S. Postal Service doesn’t have a record of delivering a package to the Austin home where the explosion occurred Monday. He said that package was brought into the kitchen where it detonated, killing a 17-year-old boy and injuring the woman.

Manley said investigators believe the explosion is linked to a similar blast that killed a 39-year-old man on March 2. That explosion occurred about 12 miles (19 kilometers) north of Monday’s blast. Both explosions occurred in the early-morning hours.

The chief said all of the victims have been black and that investigators are considering whether race could have factored into the attacks.

The FBI is helping Austin police in the investigation.