The sub shop worker held out a heavy-looking gray backpack. "Is this yours?" she asked.

Sitting at one of the restaurant's tables, Thomas G. Smith suddenly looked worried. Stocky and short-haired, he stepped toward the shop worker and asked her to put the bag down. Then he carefully looked inside.

It was a false alarm. The bag contained books, not a bomb.

Smith, 48, isn't a policeman or a terrorism expert. But he is the president of Montgomery County's volunteer Community Emergency Response Training team, or CERT, so he tries to keep himself prepared for calamity. Opportunities to serve are few. "We're waiting for the call," he said.

He also tries not to get in the way of the county's crisis responders: its police and fire and rescue personnel.

Sitting back down in the sub shop, he seemed a little bashful. He nodded in the direction of two men at another table, one with "FIRE MARSHAL" emblazoned on the back of his shirt. "I wouldn't have done that if I'd seen they were here," Smith said.

Such is the balancing act of a citizen trained for crisis in Montgomery County. Since 2003, the county has spent $150,000 in federal grants, with another $20,000 in the pipeline, to train fewer than 100 residents in how to respond to a crisis in accordance with guidelines set out by the Federal Emergency Management Agency.

The events of September 2001 added momentum to Montgomery's efforts to train residents in a variety of emergency skills, including first aid, suppressing small fires and assessing a dangerous situation.

But county officials are wondering how to keep volunteers engaged and prepared. "The real question," said Gordon A. Aoyagi, director of Montgomery's new Department of Homeland Security, "is how do we sustain the level of interest and training when you don't have that many disasters?"

The county has two other networks of volunteers ready to act in case of crisis. One is the Emergency Action Team, a group formed four years ago at a time of heightened concern over West Nile virus. Now the group consists of residents who stand ready to help out with small but important tasks, such as filling a prescription for a homebound person during severe weather or helping out at an emergency shelter.

With about 55 active members, the group has helped answer county phones during snowstorms and distribute dry ice during a power outage, said Andrea Jolly, director of the county's volunteer center.

Another group is Montgomery's year-old Medical Reserve Corps, another county response to the terrorist attacks of 2001. The corps is a network of some 400 licensed medical professionals who are ready to help out in a large-scale health crisis.

But these two groups don't face the challenges that the CERT team does. The action team members don't require refreshers for their specialized training, and the medical professionals practice their specialties in their day-to-day work. For CERT team members, it's hard to find opportunities to clear a burning building or practice basic medical triage.

With the CERT, there is also a need to foster relationships with the county's first responders, who are sometimes wary of citizens with good intentions. "To what extent," asked Aoyagi, "do you train volunteers so that they don't become so self-confident that they get in over their heads?"

Smith, the Montgomery CERT team president, made clear that "CERT is here to assist first responders; we are not first responders."

Since 2001, CERT programs have proliferated across the country, said Elizabeth DiGregorio, acting director of the community preparedness division in the U.S. Department of Homeland Security. More than 1,700 jurisdictions have registered their CERT programs with the federal agency.

"It's a program in its infancy in some of these areas," she said. "We need to give it time and make sure the first responders are comfortable with it and make sure there are roles for the volunteers to play."

"That's the big challenge," agrees Bill Delaney, a manager in the county's Fire & Rescue Service who oversees the local CERT program. He said team members could participate in smoke-alarm inspections or in counseling in neighborhoods where a serious fire has occurred.

Smith said he envisions a multitude of "mission taskings," including helping to look for lost children or adults, participating in public safety and fire safety programs, assisting with traffic control in crisis situations, and aiding in the county's response to storms and hurricanes.

The Montgomery CERT team is investigating incorporation as a nonprofit organization, in part so that it can raise money on its own. Smith would like the team to have its own radios; currently members rely on cell phones and calling trees, which may not work in a crisis.

About 48 of the nearly 100 Montgomery residents who have received the training remain active in the group, and Smith said he hopes to improve the geographic distribution of team members. Now, about half the active volunteers live in the upcounty area, just three live in the eastern county, and the remainder live in the midcounty and Bethesda-Chevy Chase areas.

A former National Guard member who is also a Red Cross volunteer, Smith said that CERT "means hope; it means you could step in and possibly help [save] someone's life." It also provides a chance to get close to the action. The Red Cross stays on the edges of a crisis, in the "cold zone," Smith said. If a crisis should occur, he added, the CERT team would function in the "hot to warm zone."

Capt. Mark Bird, of the Montgomery County Fire & Rescue Service, shows Community Emergency Response Training team members how to use a fire extinguisher at a class in Rockville. Below, Bird instructs the class before the demonstration.

Gene Ushinski, top, a volunteer with the American Red Cross, talks to volunteers gathered for a training session in Rockville. Ushinski is retired from the Federal Emergency Management Agency. Ann Reiss, below, director of the Montgomery County Medical Reserve Corps, answers questions from volunteers during a training session in Rockville. At bottom, a dummy serves as a trapped "victim" for CERT trainees to find and rescue.