As world leaders gathered Monday in Washington, D.C., to discuss the threat of nuclear terrorism, local officials said they are gearing up for an exercise in June that simulates the detonation of a 10-kiloton nuclear device in Los Angeles.

Mike Contreras, director of emergency operations for the county Department of Public Health, said the county and city are preparing for "Golden Phoenix" to test the ability of police, fire and other agencies to respond to a catastrophic incident.

"We in Los Angeles County are working hard to try to prepare for such an event and have a response in place," Contreras said. "This exercise, Golden Phoenix, is really our first step in taking a look at this problem and seeing what kinds of things we need to do to be ready for this."

The exercise, involving emergency operations officials from cities countywide, will give local agencies a chance to learn when it's necessary to evacuate areas of the Los Angeles basin that are not affected by initial radioactive fallout.

After the detonation of a nuclear bomb, the wind would carry the plume in a certain direction. Through the exercise, officials hope to learn how to best notify the public of whether to evacuate or to shelter in place.

"We're working to see what tactics we would need to apply to save lives," Contreras said. "That's the big thing - looking at it from the perspective of 'It's a catastrophic event and what can we do to minimize the impact'."

The exercise comes as President Obama meets with world leaders through today for the first-ever Nuclear Security Summit to focus securing nuclear weapons and related raw materials worldwide to prevent them from falling into the hands of terrorists.

President Obama has labeled nuclear terrorism a "threat that rises above all others in urgency."

A report issued Monday by Harvard University's Belfer Center for Science and International Affairs predicted that unless the world acts with great urgency there is a greater than 50 percent chance that terrorists will use a weapon of mass destruction somewhere in the world by 2013. The report noted that al Qaeda has threatened to kill 4 million Americans and has sought nuclear weapons for more than a decade.

Michael Intriligator, a terrorism expert and a professor of economics, political science and public policy at UCLA, said al Qaeda has named Los Angeles as one of its top two targets. Intriligator said the detonation of an improvised nuclear device at the Los Angeles and Long Beach ports could kill 1 million people and cripple the nation's economy.

"They are trying to outdo 9-11," Intriligator said. "They are looking for weapons of mass destruction - whether it's nuclear, chemical or biological - that would be more spectacular and kill more people than 9-11."

Sheriff's Department Sgt. Scott Anger, a terrorist expert, said local, state and federal officials in Los Angeles are working on plans and taking steps to try to prevent terrorists from ever using a weapon of mass destruction here.

"To that end, we do have radiological as well as nuclear detection capability and interdiction capabilities," Anger said.