A family in Portland, Ore., received a nightmarish phone call two weeks ago.

“Unplug your Alexa devices right now,” a voice on the other line said. “You’re being hacked.”

Apparently, one of Amazon.com’s Alexa-powered Echo devices in their house had silently sent recordings to the caller without the family’s permission, according to KIRO 7, a news station covering Seattle and western Washington state that first reported the story. The person, an employee of the husband, was in the family’s contact list.

“My husband and I would joke and say, ‘I’d bet these devices are listening to what we’re saying,’ ” a woman who identified herself only by her first name, Danielle, told KIRO. She added that the device did not tell her that it would be sending the recorded conversations.

Amazon said in an emailed statement to The Washington Post on Thursday afternoon that the Echo woke up when it heard a word that sounded like “Alexa.” “The subsequent conversation was heard as a ‘send message’ request. At which point, Alexa said out loud ‘To whom?’ At which point, the background conversation was interpreted as a name in the customer's contact list."

The company also said, “As unlikely as this string of events is, we are evaluating options to make this case even less likely.”

(Amazon’s chief executive, Jeffrey P. Bezos, owns The Washington Post.)

This isn’t the first time that Amazon's smart speaker has garnered scrutiny over potential eavesdropping. Last month, researchers discovered a flaw in the Alexa voice assistant, enabling an Echo to continue listening to people without them knowing. The devices are supposed to record audio only after users issue a voice command, known as a “wake word.” Amazon quickly fixed the vulnerability after researchers alerted the company.

Wenchao Zhou, a computer science professor at Georgetown University, said the Portland episode demonstrates how machines “can wrongly interpret human voices.” In addition, voice assistants can respond to sounds that humans cannot hear and misinterpret background conversations as commands, he said.

Daniel Kahn Gillmor, a staff technologist for the American Civil Liberties Union's Speech, Privacy and Technology Project, said that the intuitive nature of connected devices can mask their complexity and the possibility of malfunction. “The Amazon Echo, despite being small, is a computer — it’s a computer with microphones, speakers, and it’s connected to the network,” he said. “These are potential surveillance devices, and we have invited them further and further into our lives without examining how that could go wrong. And I think we are starting to see examples of that.”

Do you have a similar story? If so, please email me at hamza.shaban@washpost.com.