****** 5月13日のブロガーサービス不具合により、当日の投稿が出来ませんでした。 ******
という意味でも用いられます。American Heritage Dictionaryでは、
To limit the activity or influence of by or as if by creating a restrictive structure or outlining a territory
Border agents killed by train during chase in Arizona
Two U.S. Border Patrol agents chasing a group of suspected illegal immigrants were killed early Thursday after their SUV was struck by a freight train near Gila Bend, Ariz., about 80 miles north of the Mexico border.
Hector Clark, 39, and Edward Rojas, 34, were assisting other agents in the early-morning chase when they attempted to cross the tracks ahead of the 4,600-ton train, said Robert Lowry, an agency spokesman.
Both agents died at the scene.
The crew aboard the westbound Union Pacific freight train saw the vehicle driving on a frontage road north of the tracks when the unmarked SUV suddenly turned south onto a private crossing immediately in front of the fast-moving train, said Aaron Hunt, a Union Pacific Railroad spokesman.
Clark and Rojas attempted to cross the tracks to "box-in" the group of suspected illegal immigrants, Lowry said.
Typically, trains on that stretch of rail travel upwards of 40 mph and require at least half a mile to come to a complete stop. The train struck the vehicle on the driver's side and pushed it for at least a half-mile.
(Stephen Ceasar. Border agents killed by train during chase in Arizona. Los Angels Times. May 12, 2011.)