"There is no current threat to our community and we are working to determine exactly how/why the sirens were activated," the city's fire department said on Twitter.
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The police department also confirmed "the tsunami alarm this morning was a false alarm."
According to Huntington Beach's official website, the sirens are located at all eight of the city's fire stations and are tested on the first Friday of each month at noon.
"If you hear the sirens, and it is NOT the first Friday of the month, turn on your television and radio (107.9 FM, KWVE) and await further instructions," the website says.
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Several residents took to social media after being awakened by the errant sirens.
"Well someone in Huntington Beach CA forgot to change the time for the Tsunami warning test," John San tweeted. "What a wakeup call at 4 a.m. I know what it sounds like now."