More than 160 Air Force Reserve pilots and crew members reported for active duty yesterday at Andrews Air Force Base, and about 1,000 reservists from Virginia, Maryland and the District were told they are likely to be called up shortly because of the Persian Gulf crisis.

The 97th Army Reserve Command, based at Fort Meade, yesterday afternoon alerted seven Maryland and District units totaling 429 people to prepare for active duty, said Lt. Col. Sue Dueitt. They could be activated as soon as within two or three days, or wait several weeks, she said.

A 36-person Southwestern Virginia National Guard unit and a 110-person Maryland National Guard military police unit based in Towson also received word to get ready for active duty, although they also may not begin serving for several days.

News of the alerts trickled in haphazardly, as new units were alerted faster than spokesmen could keep track of them. The First Army, also based at Fort Meade, announced the call-up of two National Guard units based in the District and four Army Reserve units from Virginia, totaling about 470 members.

On Thursday, Secretary of Defense Richard B. Cheney authorized the mobilization of 49,703 of the nation's 1.16 million reservists by Oct. 1. Activated reservists serve 90 days, and the president can extend their tours of duty by 90 more days. There are more than 70,000 eligible reservists in Virginia, Maryland and the District.

"We were looking at the odds as one in 100,000. It's unfortunate we haven't been playing the lottery, because it looks like we're the winners," said Capt. Paul Dalton, of the Virginia National Guard's 1030th Engineering Battalion.

At Andrews, the call-up of the 756th Military Airlift Squadron began just after midnight yesterday, startling many squadron members out of their sleep.

"I got called at 2 a.m. and the guy started reading me the order . . . 'You have hearby been called up by the president of the United States,' " said Joe Alto, 29, of Fort Washington. "It was too formal. I just wanted to know what time."

The squadron, one of only five Air Force Reserve units in the nation to be activated yesterday, will ferry C-141 cargo planes full of people and equipment to the Persian Gulf and elsewhere, members said.

The newly activated troops at Andrews yesterday worried about getting immunized. "Do I have to get cholera? . . . . What's the one that starts with G?" asked one. "Gamma globulin," answered another.

After checking in, most took the rest of the day to set their affairs in order. They are to receive detailed assignments this morning.

Many squadron members, who are mostly in their thirties and late twenties and include commercial pilots and government employees, have already been to the Middle East this month, because they had volunteered for shorter missions.

"I just got back this morning. When I called my wife, it was good news, bad news," said Capt. Ken Wessel of Lake Ridge. "I'm back, but I've been activated."

Going on active duty will cause some hardships, because it means at least three months without seeing their families, and subsisting on military salaries -- a substantial pay cut for many reservists.

"I have a mortgage, and I've been making calls all morning" to arrange to temporarily reduce the monthly payments, said Tech. Sgt. Mike Corrado, of Laurel. "I'm glad it happened during the week, because financial institutions are open."

Fathers said they worry what their children are thinking.

"I have a 4-year-old daughter. She watches television {and} every time she sees an airplane she says, 'There's Daddy,' " said Staff Sgt. William Gray, a Roanoke police officer. "She knows guns hurt people," said Gray, whose family "has got a yellow ribbon tied around the tree already."

The four Virginia Army Reserve units to be called up include the 344th Data Processing Unit, a 40-person unit based at Fort Belvoir, and three Hampton units, the 91st and 145th Transportation Detachments, and the 359th Transportation Battalion, with a total of 129 soldiers, said Maj. Charlotte E. Vaughn, of Fort Belvoir.

The District National Guard units include the 547th Truck Company and the 380th Supply and Service Company, totaling more than 300 people, said Maj. Phyllis Phipps-Barnes. A District Army Reserve Judge Advocate General's unit of eight legal experts specializing in procurement also has been placed on alert, Col. Dueitt said.

The Fort Meade call-up included six Maryland units: the 450th Civil Affairs Company, based in Riverdale; the 400th Military Police Battalion, based at Fort Meade; and four Baltimore units: the 1176th Transportation Terminal Unit, the 313th Transportation Corps Battalion, and the 200th and 202nd Transportation Corps Detachments.

None of the units knows where it will be going.

The Maryland National Guard unit, the 290th Military Police Company, is trained to provide security at key installations and perform law enforcement missions, said Maj. Gen. James F. Fretterd, adjutant general of the Maryland National Guard. About 10 percent of the unit is made up of state and local police officers.

Virginia's activated National Guard battalion, which recently won a national award for excellence, serves as a command post for other units that build roads and bridges, said training officer Dalton, adding, "We're just hillbillies. We take training seriously."

Staff writers John F. Harris and Richard Tapscott contributed to this report.