NBC Nightly News with Brian Williams

BREAKING NEWS: Federal judge declares Arizona’s ban on same-sex marriage unconstitutional; decision takes effect immediately. With ruling in Arizona, the number of states that permit same-sex marriage is now 31, NBC’s Pete Williams reports.

BREAKING NEWS: President Obama to appoint Ron Klain, former chief of staff to VP Biden, as Ebola czar, NBC News has learned

BREAKING NEWS: Dow falls more than 400 points in its worst day since November 2011 http://nbcnews.to/1vvS1w6

BREAKING NEWS: Dow falls more than 400 points in its worst day since November 2011 http://nbcnews.to/1vvS1w6

BREAKING NEWS: Dallas Ebola patient Thomas Eric Duncan has died, hospital says

BREAKING NEWS: Dallas Ebola patient Thomas Eric Duncan has died, hospital says

BREAKING NEWS: Some U.S. airports to conduct additional screening on travelers arriving from West African nations most affected by Ebola; passengers will have their temperatures taken and have to fill out a questionnaire

BREAKING NEWS: Secret Service Director Julia Pierson has resigned, Homeland Security Secretary Jeh Johnson announces

BREAKING NEWS: Secret Service Director Julia Pierson has resigned, Homeland Security Secretary Jeh Johnson announces

JUST IN: U.S. military and partner nations carrying out additional airstrikes against ISIS targets in Syria; operation ongoing, Pentagon says

BREAKING NEWS: U.S. military launches first airstrikes against ISIS targets in Syria, NBC News confirms