SAN BERNARDINO >> At a secluded San Bernardino County warehouse, a 53-foot tractor-trailer delivered 17 pallets of pretend antibiotics Wednesday morning for what officials called the largest mock bioterrorism drill in the state’s history.

The event has been planned for at least 18 months, although some elements being tested were put into place a decade before, officials said.

Those “medicines” will be delivered today to first-responders and hospitals, for employee use, in the morning and in the afternoon. There will be a practice distribution to the “public” — at the Chino Neighborhood Activity Center — which will include actors pretending to have some of the early symptoms of anthrax.

The Southern California Regional Exercise for Anthrax Disaster Incidents, called SoCal READI, for short, began about 8 a.m. with a pretend spraying of aerosolized anthrax along the coast of San Diego and Orange counties, said Dr. Mawell Ohikhuare, health officer for San Bernardino County.

Unprecedented SoCal READI drill involves the California Department of Public Health, health departments and other agencies in the counties of San Bernardino, Los Angeles, Riverside, Orange, San Diego, Imperial, Inyo, Mono, Ventura, San Luis Obispo and Santa Barbara counties. Health departments in the cities of Long Beach and Pasadena area also participating, state officials say.

Part of the coordination between counties is to ensure that medication distribution occurs at the same time everywhere, Ohikhuare said.

That will avoid large scale panic migrations of from one county to another.

The bacteria that causes anthrax would be one of the biological agents most likely used in a bioterror attack, says the federal Centers for Disease Control and Prevention.

Inhaled anthrax is the most deadly form of the disease, CDC officials say.

Although the drill is large, it is nowhere near the operational scale that would be assembled in a real event that involves possible exposure for 25 million Californian residents, state and San Bernardino County officials say.

In the real thing, the 17 pallets would be more like 225 and take as many as five tractor-trailers to carry into town, said Matt Baca, who directs the county’s Preparedness & Response Program.

Nevertheless, the drill, as it plays out at the Chino activity center on Thursday, will have realism, with a strong presence of law enforcement to protect antibiotics which might have a huge black market values in a real event, Ohikhuare said.

The medical personnel at the center will be pushing “medications” “as fast as they can. There will be no proof of residency required. Just be living and a person and you will get ‘medicine’,” he said.

A sophisticated field deployed electronic inventory recording system will be tested today. It will record not only how many pills have been dispensed, but who received them, said Glenn C. Demerdieros business systems analyst with the county health department.

“This is mostly in case a lot (of the antibiotics) is recalled. It would give us a way to notify certain people, Demerdieros said.

Ohikhuare said that the experience gained from this drill will carry over to other situations, such as an outbreak of a new strain of flu.

The time frame of the response is much slower in the drill than what would happen in a real bioterrorism attack, officials say.

During the drill, work stops about 5:30 p.m. every day, Baca said.

In a real scenario, work would continue around the clock and the truck with medicines would have arrived Tuesday, he said.

“It is important that people start taking antibiotics (due to anthrax exposure) within the first 48 to 72 hours, Ohikhuare said.

Medications taken after symptoms occur generally don’t work, public health officials say.

Inhaled anthrax survival rates are 10 percent to 15 percent without treatment, according to the CDC website.

Elements of the bioterrorism drill continue through Friday, officials said.

In San Bernardino County, participation in the drill included county departments of health, fire hazmat, sheriff, Offices of Emergency Services, and the Inland Counties Emergency Medical Agency, which includes Inyo and Mono counties.