"Primarily, we were involved in emergency transportation," in February, when troops transported patients for dialysis and other essential care, Kohler said. They also removed snow from Baltimore City streets. Officials are taking a wait-and-see approach with Isabel, making Guard troops available to move when and where they are needed.

"It's really going to be driven based on what's happening," Kohler said.

"We're planning on repositioning soldiers to areas that are hit hardest," he said. "And that's not uncommon to do that in operations, to plan on moving your forces as necessary."

But the Guard will have help: The Federal Emergency Management Agency is aiding Maryland and other states in Isabel's path, dispatching emergency-response crews and disaster-relief supplies throughout areas affected by the storm, according to a news release. FEMA is also coordinating emergency-response efforts with the Red Cross, which had activated a "hurricane watch team" Wednesday, said Ruth L. Tyler, a spokeswoman for the central Maryland chapter.

The Hurricane Watch Team "monitors hurricanes and plans, prepares and mobilizes both human and material resources before a hurricane hits," said Kevin Burr, emergency services director for the Baltimore-based chapter, in a printed statement.

The Red Cross is also working with the Guard to coordinate disaster-relief efforts.

Power companies were also preparing to respond to outages caused by downed power lines. Pepco, which came under heavy criticism recently when storms left some Montgomery County residents without power for several days, cautioned customers to prepare for outages.

Utility crews from other states were arriving in Maryland as early as Wednesday, as power companies planned to work around the clock to deal with outages.