A gunman opened fired from a hotel room at an outdoor concert in Las Vegas, killing at least 50 people and injured more than 400 others -- prompting mayhem as crowds of people scrambled for safety.

According to authorities in Las Vegas, Stephen Paddock, 64, was found dead in his room on the 32nd floor of the Mandalay Bay Resort and Casino.

►Related: Who is Stephen Paddock? Police say he killed 50 in Las Vegas shooting rampage
►Related: Concert video captures terrifying moments of gunfire during Las Vegas concert

Panic ensued on the ground, as crowds were scrambling for shelter. Off-duty San Diego Police Officer, Tom McGrath, who was attending the Jason Aldean concert that evening, was in the midst of the shooting -- trying to stay safe while helping others.

Officer McGrath shared some of his experiences with WZZM 13 on Monday morning. McGrath, his wife and the the people with them were not injured -- however, officials are calling this onslaught the deadliest mass shooting in U.S. history.

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April Stevens is a multi-platform producer at WZZM 13. Have a news tip? Email news@wzzm13.com, visit our Facebook page or Twitter.