Crime has its ups and downs, especially in the Washington area, where there have been six robberies in elevators this week.

Eleven people aboard an elevator in a Rosslyn high-rise were robbed of a total of $350 Thursday afternoon by two unseen thieves atop the car who stopped the elevator between floors, sprayed them with a fire extinguisher, told them to lie on the floor and hand over their cash.

The drenched victims who did as they were told and were apparently unhurt, told Arlington police they gave their money to one of the tallest men among them who handed it up to the outstretched hand of one of the phantom thieves through a grate in the elevator roof.

It was the sixth such robbery reported in the area this week and the second in Arlington, Arlington Detective Edward Sheroshick said yesterday. Thursday's robbery occurred at 1400 Key Blvd. in a building housing the State Department's Foreign Service Institute.

"Let's put it this way: I hope it's the same guys," said Sheroshick. There was a similar robbery in a high-rise medical building located on Wisconsin Avenue in Montgomery County and several in buildings near New York Avenue NW in the District, he said.

On Monday, five people on their way to lunch in Rosslyn were robbed of $74 by a thief or thieves atop an elevator car in a building at 1700 N. Lynn St.

Police said Thurday's incident clearly was well planned because the thieves cut the emergency telephone line in the elevator and had disabled the building's other two elevators.

Passengers said the elevator began jerking and then stopped suddenly between the third and fourth floors. "One victim pressed the alarm button and tried to use the security phone but the line had been cut," Sheroshick said. "Another heard some people walking on top of the elevator and talking and thought it was repairmen so he removed the paneling from the top of the elevator to assist."

The group then was sprayed with the fire extinguisher, ordered not to touch the alarm button and robbed. The robbers got off the elevator on the fourth floor and their victims were rescued a short time later by a security guard who pried open the elevator doors.

"The normal John on the street wouldn't be familiar with the operation of elevators," said Sheroshick, who said he suspects the thieves are maintenance men or elevator repairmen.