The gunman is hiding in farmland after a chase with the police.

WILMINGTON, Ohio — When Rob Thompson left to run errands shortly after 10 a.m., he was greeted at the end of his driveway by a speeding white Crown Victoria being pursued by several police officers.

“I thought, since we are by the interstate, that they were just chasing a speeder,” said Mr. Thompson, who said his family has owned and farmed 4,000 acres near Wilmington, Ohio, for three generations.

He soon learned that the man being chased, who stopped about half a mile from his driveway at the edge of a cornfield, was wanted for trying to breach the F.B.I. Cincinnati Field Office. The tall corn blocked his view of the standoff, but he went to the top of his grain bins for a better look.

“He could be in the cornfield or a thicket of trees nearby, but they have him contained,” said Mr. Thompson, who said he was not concerned about his safety.

Still, the chase disrupted daily life in the area. Rob’s brother, Bill Thompson, said he had been prevented from delivering pig feed to the farm. He was waiting at a nearby grill for the standoff to end.

“We are going to have some hungry pigs,” he said.