Empty pill bottles like this were distributed to 37,000 households in the Twin Cities metro area on Sunday, May 6, 2012 as part of an emergency planning exercise. MPR photo/Elizabeth Dunbar

The Minnesota Department of Health and U.S. postal workers responded to a fictional airborne anthrax attack in the Twin Cities this weekend. The scenario is designed to prepare officials for a biological terror attack.

Officials called the test a success. "Operation Medicine Delivery" was the first full-scale test of a strategy for distributing medicine in the event of an epidemic or large-scale anthrax attack. About 300 mail carriers on Sunday delivered empty pill bottles to thousands of homes in parts of St. Paul, north Minneapolis, Robbinsdale, Crystal and Golden Valley.

Claire Thompson is one of those who found a small white pill bottle in her mailbox Sunday. The label said "This is only a test."

Thompson handed the empty bottle to her 1-year-old child and it immediately became a toy. The family got a flier in the mail a week ago telling them to expect the bottle.

"The flier was talking about something like in case of a bioterrorist attack or something," she said. "It kind of made me giggle because it had never occurred to me before, and I guess I'm glad someone thought of it because it wasn't me." Once she did start thinking about it, Thompson realized she has lots of questions.

"How would they know how much medication to deliver to a home? Where are you going to get this stockpile anyway? I assume if everybody is so sick they can't leave their house, how you going to count on your mail service? I can tell you, I'm not going to go and watch 'Contagion' this evening," she said with a laugh.

Minnesota Health Commissioner Dr. Ed Ehlinger speaks at a news conference about an exercise Sunday that tested the state's ability to distribute pill bottles in an emergency. MPR photo/Elizabeth Dunbar

"Contagion" is a movie released last year about a virus that becomes a public health crisis for doctors from the Centers for Disease Control and Prevention.

A good part of the movie is set in Minnesota, where federal officials said the Health Department is well prepared for a bioterror outbreak. Edward Gabriel, an official of the U.S. Department of Health and Human Services, was in town in advance of this weekend's test.

"The Twin Cities are the only metropolitan area in this country to reach this step in preparation," he said. "Minneapolis, St. Paul, the state of Minnesota, on behalf of the Department of Health and Human Services and the White House, I thank you for your leadership in this effort."

Three years ago, President Obama issued an executive order to establish a model where postal workers would deliver medication during a large-scale biological emergency. The idea is to keep crowds from flocking to medicine distribution centers.

In the order, the president suggested the Postal Service because it "has the capacity for rapid residential delivery" after a biological attack.

A $200,000 federal grant paid for the Twin Cities test, which will serve as a model for other cities. Minnesota Commissioner of Health Ed Ehlinger says a large-scale threat that would trigger use of the postal plan is rare.

"But it's also the kind of event that could have devastating consequences in our communities if it did occur and we weren't ready for it," Ehlinger said.

If a bioattack scenario were real, more than 3 million people in the greater Twin Cities area might need medication.

The weekend exercise targeted 37,000 households. Teams of postal workers made the deliveries with police escorts. At least 76 homes in Robbinsdale were skipped because of flooding in their neighborhoods.

"I don't think it's too early to say it was largely successful," said Department of Health spokesman Buddy Ferguson. "But it's going to take time to measure the degree of success and determine what limits there are to this particular way of getting medicine to people."

Ferguson said in a real biological attack, the people distributing medication would be among the first to get the antibiotics. And he said home delivery would be one of many distribution methods.