A couple's private conversation was mysteriously recorded by their Amazon Echo device and sent to one of their contacts, igniting privacy concerns about the voice-activated gadgets the online retailer wants to make as commonplace in homes as televisions.

The two found about it when they received a phone call two weeks ago from one of the husband's employees telling them to "Unplug your Alexa devices right now. You're being hacked," news station KIRO 7 reported. Amazon.com Inc. said in a statement to the station that it was an "extremely rare occurrence."

The Portland, Oregon, couple used Amazon's voice-activated devices throughout their home to control heat, lights and the security system, according to the news report. Amazon in 2014 introduced the new line of devices, which can also stream music and order goods from Amazon via voice command. It has been busy introducing updated versions and adding features to sell more devices than rivals like Alphabet Inc. and Apple Inc., which are rolling out their own versions.

People have been willing to overlook glitches in the Echo, like it turning on accidentally or without the wake word being uttered, said Ryan Calo, an associate law professor at the University of Washington who researches how law applies to technology. This incident is more alarming since a private conversation was recorded and sent to a third party, he said.

"Think about how uncomfortable the millions of people who own these things now feel," Calo said. "The real harm is the invasion into solitude people now experience in their homes."