Today, Sept. 11, 2013, marks 12 years since the day the world changed when coordinated terror attacks took down the World Trade Center towers in NYC, while a third plane crashed into the Pentagon. Another plane crashed in a field in Pennsylvania in a thwarted mission, as passengers attempted to take over the flight.

It's a somber day of reflection, filled with #NeverForget and #AlwaysRemember hashtags, as thousands of Americans and first responders lost their precious lives. We remember and pray for them.

Some pop stars shared their pain and their memories on Twitter, like Lady Gaga, who is a native New Yorker.

Our thoughts go out today to those who lost loved ones and were affected by this tragic event.