Beaches along Nassau County re-opened, but with an urgent message of caution after 33-year-old lifeguard, Zack Gallo was attacked by a shark. Gallo was mimicking a swimmer in distress as part of a training exercise. Records dating back almost 200 years show shark attacks are rare, with most happening around popular surfing beaches like New Smyrna, Florida, where another shark bite occurred yesterday. Experts say that the recent spate of attacks is more likely a consequence of more people in the water.  » Subscribe to NBC News: http://nbcnews.to/SubscribeToNBC » Watch more NBC video: http://bit.ly/MoreNBCNews NBC News Digital is a collection of innovative and powerful news brands that deliver compelling, diverse and engaging news stories. NBC News Digital features NBCNews.com, MSNBC.com, TODAY.com, Nightly News, Meet the Press, Dateline, and the existing apps and digital extensions of these respective properties. We deliver the best in breaking news, live video coverage, original journalism and segments from your favorite NBC News Shows. Connect with NBC News Online! NBC News App: https://apps.nbcnews.com/mobile Breaking News Alerts: https://link.nbcnews.com/join/5cj/breaking-news-signup?cid=sm_npd_nn_yt_bn-clip_190621 Visit NBCNews.Com: http://nbcnews.to/ReadNBC Find NBC News on Facebook: http://nbcnews.to/LikeNBC Follow NBC News on Twitter: http://nbcnews.to/FollowNBC Follow NBC News on Instagram: http://nbcnews.to/InstaNBC #Sharks #Lifeguard #nassaucounty