An unknown person appeared to throw some kind of smoke bomb over the White House fence last night during a demonstration by Occupy protestors outside the main gates. The Secret Service briefly put the building on lockdown, even though the President and First Lady were not at home. (They went out to dinner to celebrate Michelle Obama's 48th birthday, but returned without incident.) About 1,000 to 1,500 protesters were quickly dispersed and no arrests were made. The rally was an aftershock of the larger Occupy Congress protest in front of the Capitol building earlier in the day. Organizers had hoped to get 10,000 people for that rally, but according to Fox News they fell well short of the goal. Four people were arrested near the capital, but police and protesters avoid any serious conflict.