By Jon Herskovitz
AUSTIN, Texas (Reuters) - Police have received more than 150 calls about suspicious packages after three parcel bombs left outside homes in Austin, Texas, exploded this month in related attacks that killed two people and injured two others, officials said on Tuesday.
No motive has been given for the blasts - two of which took place on Monday following one on March 2 - when parcels left in front of residences in three separate neighborhoods exploded.
Two of the packages detonated at homes where African-American people live and the third was at the home of a Latina woman, raising the possibility the attacks were hate crimes, police said. The deaths are being investigated as homicides.
"My prayers are with the families of those that lost their life or injured during the three explosions. The investigation into the incidents is ongoing," Austin Police Chief Brian Manley said in a tweet on Tuesday.
The packages that exploded on Monday were not delivered by any mainstream commercial shipping services, such as FedEx or United Parcel Service, Manley has said.
He warned residents to watch out for boxes left outside their homes and to report anything suspicious to police.
The first explosion, on March 2, killed Anthony Stephan House, a 39-year-old black man, at a house in the city's Harris Ridge neighborhood, which is home to technology companies and about 12 miles (19 km) northeast of downtown. The blast was powerful enough to blow out a wall at the home's entryway.
A 17-year-old African-American boy died on Monday when he found a package outside his house in east Austin and brought it into the kitchen, where it exploded, Manley said.
A woman in her 40s was in the home and was injured by the blast, although she was expected to survive, police said.
A second explosion, about 4 miles away in southeastern Austin, injured a 75-year-old woman in the working-class Hispanic community of Montopolis.
Monday's attacks occurred as hundreds of thousands of visitors thronged the city for the South by Southwest Festival of music, technology and film.
"We are all scared. If you get a package don't open it, man," said Julian Pina, 56, and a tile setter who lives about 100 yards (91 meters) from the spot where the bomb went off that injured the 75-year-old woman.
(Reporting by Jon Herskovitz; Editing by Susan Thomas)