Singer Leann Rimes, Billy Ray Cyrus and actress Olivia Munn have offered their thoughts and prayers to those caught up in a deadly shooting at the U.S. Naval Yard in Washington, D.C. on Monday morning (16Sep13). At least one gunman is reported to have opened fire at the Naval Sea System Command Headquarters, causing multiple deaths and injuring at least eight others, including a D.C. police officer. Conflicting reports suggest one suspect was killed at the scene and authorities are on the hunt for two other "potential" gunmen who remain at large. Official casualty numbers had yet to be released as WENN went to press. The news prompted an outpouring of emotions on Twitter.com, with celebrities also weighing in on the latest mass shooting in America. Country star Rimes writes, "The news of the navy yard shootings is horrific. Prayers go out to everyone involved & touched by this tragedy. So sad!", while TV star Melissa Joan Hart posts, "Prayers going out to the Washington Navy Yard today! Unbelievable how often these shootings are happening!!" The Newsroom beauty Munn tweets, "My thoughts are with everyone in D.C.", while Miley Cyrus' dad Billy Ray laments, "Woke up to another shooting in America.This one on the news. How many others we won't even hear about? Pray for our country. Kids need 'HOPE'", and singer Mya writes, "Nightmares of violence night after night all to wake & discover it's just daily reality on earth. Praying for humanity on planet earth". Monday's tragedy comes less than a year after America was rocked by the Sandy Hook school massacre in December (12), when 20 young children and six adults were murdered.