The LAPD Police officers were involved in a standoff outside the Federal Building in West Los Angeles with a man suspected of making threats against the White House.  Police had chased the man through the West Side of Los Angeles until the chase eventually brought them to the site of the standoff.  Evacuation of a nearby apartment house and the use of a four-wheeled robot to scan for bombs have been undertaken as precaution during the standoff. Read more on this 

http://www.postchronicle.com/news/original/article_212250821.shtml

http://www.washingtonexaminer.com/nation/ap/53154137.html