What to know this morning: In 5 minutes or less

1. Four passengers injured in the Amtrak crash in Philadelphia last week have filed a federal lawsuit against the U.S. rail service, citing "serious and disabling" injuries from the crash that killed 8 and injured over 200. Read more here.

2. More details are emerging around the deadly shootout in Waco, Texas, suggesting that violence has long simmered between the two biker gangs. All nine people who were killed in the fight were members of either the Cossacks or the Bandidos. Read more here.

3. "It's Barack. Really!" President Obama has just joined Twitter and already has almost 2 million followers. See his first tweet below!

4. The State Department will release parts of 55,000 emails sent by former Secretary of State Hillary Clinton by January 2016. The fact that the Democratic front-runner used her personal email address for State matters was a point of controversy, and Clinton has said she'd like the emails to be released as soon as possible. Read more here.

5. The fight of the century has become a fight in court -- boxing fans across the country (and their lawyers) are calling the Mayweather vs. Pacquiao fight a "fraud" and are heading to court to get their money back. Read more here.

6. In case you missed it, Leighton Meester and Adam Brody are expecting a baby! Read more here.