02/24/2012 02:32 pm ET Updated Feb 24, 2012

Teen Saves A Life Using Tumblr (VIDEO)

Social-networking sites can be used for both positive and negative purposes, but in some incredible cases, social media has even been used to save lives. When a stroke of fate recently touched the lives of two girls, that's exactly what happened.

Nineteen-year-old Anna Clark, a student at Northern Kentucky University, was browsing various blog posts on Tumblr one Sunday night, when she came across a startling entry,. The post, written by 16-year-old Laura from Michigan, read: "I just swallowed a bunch of pills." Anna scrolled through the rest of the entry, and came across some other words that raised red flags, such as "goodbye," WCPO 9News reports.

Anna did not personally know Laura, outside of the one time they met briefly at a convention in Columbus, Ohio. But instead of passively ignoring the post, Anna acted on her instincts and sought out help. After receiving Laura's contact information from some online friends, Anna woke up her mother and called the local police. They connected her to a precinct in Michigan, and managed to save the teen's life.

Anna's act of courage and quick-thinking isn't the only recent instance of one teen saving another's life via social networking sites. Earlier this month, 17-year-old Danny Manes sent a Facebook message to a peer he casually after reading a suicidal-sounding status, and he ended up saving the teen's life. Following the incident, Manes and his friend, Gary Ramirez, started an anonymous teen advice page on Tumblr called "Hopeline for Teens."

And just yesterday, Tumblr announced that it would be revising its content policy, effectively prohibiting blogs that promote self-harming behavior such as eating disorders, self-mutilation, and suicide. The new will also display public service announcements alongside search results for keywords related to self-harm.