Police in Austin have been inundated with suspicious package calls since two package explosions Monday left a teenage boy dead and two women hospitalized.
In less than 24 hours, Austin police received at least 150 such calls, according to a tweet from Austin Police Chief Brian Manley.
Police told the Austin American-Statesman that nothing suspicious was found regarding any of the calls.
Meanwhile, authorities say the bombs detonated Monday were "sophisticated," the Washington Post reports. Manley told Austin station KXAN that the suspect or suspects have been able to construct and deliver the bombs without setting them off and that the bombs only detonate when handled by their recipient.
"There's a certain level of skill and sophistication that whoever is doing this has," Manley said.
Three package explosions, two Monday and one March 2, killed a 39-year-old African-American man and a 17-year-old African-American boy, and critically injured an African-American woman in her 40s and a 75-year-old Hispanic woman.
CNN reports that the two male victims are related to prominent members of the African-American community in Austin. Police say this may indicate that the package bombings are hate crimes.