The simulated terrorist attack began in Seattle, Washington State with the explosion of a fake radioactive "dirty bomb," the dispersal of radioactive material by conventional explosives, in a car in an industrial lot.

Meanwhile, a fake car bomb exploded about 40 miles (about 68 kilometers) to the south and a terrorist ran into a university campus building and took hostages.

Three minutes after the explosion at 3:00 p.m. EDT (1900 GMT), fire and emergency vehicles started arriving to deal with three wrecked buses overturned nearby and four blazing cars. Firefighters put out fires within 22 minutes. The two explosions were supposed to cause more than 100 "casualties."

The drill, which is being overseen by the Department of Homeland Security in conjunction with the State Department, will cost an estimated 16 million US dollars and involve about 8,500 officials from more than 100 local, state and federal agencies, the American Red Cross and agencies from the Canadian government.

It has been the first large-scale counter-terrorism exercise since the September 11 terrorist attacks against the US in 2001.

A similar test involving a simulated biological attack is scheduled for later this week in Chicago, Illinois, 2,735 kilometers (1,700 miles) away from Seattle. Over the next few days,a number of "patients" with flu-like symptoms will show up at hospitals in the Chicago area after a terrorist group releases a deadly plague in aerosol form.

The simulated biological attack was dubbed "Topoff 2" for top officials. The first such drill, "Topoff 1," which was conducted three years ago in Denver and New Hampshire, was plagued by communications and coordination problems between federal, state and local officials.

Hundreds of evaluators will watch the exercises and report their findings for later study.

Letters and public service advertisements were issued during the weekend to tell residents in both cities about the drill.

No explosives or harmful devices were used during the drill, but participants were expected to fill the roles they would have in a real emergency.

Homeland Security chief Tom Ridge remained in the White House to keep President George W. Bush, who is visiting several US states this week, informed by telephone.

Ridge said the exercise was aimed to "measure and analyze a response to a terrorist attack."

Twenty months after the September 11 attacks, efforts are accelerating in the US to enable states and cities to respond aggressively to the next possible terrorists strike on a large scale.

(Xinhua News Agency May 13, 2003)