Dee Hughes was washing dishes in the kitchen of her Glenn Dale home in Prince George's County last month when she heard a helicopter hovering close overhead. Next, an ear-shattering explosion shook the house, knocking a pane of glass out of the front door and panicking one of her prize Arabian stallions, which bolted through a paddock fence.

"I thought a plane had crashed on my property," recalled Hughes, whose Glenn Dale Road neighbor, Betty Royster, returned home to find two windows shattered.

In fact, the racket came from the grounds of the neighboring abandoned Glenn Dale Hospital where District police and the Secret Service recently started conducting training exercises.

The hospital, which is owned by the District and was built in the 1930s as a tuberculosis sanitarium and later served the chronically mentally ill and disabled, closed in 1982. Its 26 brick buildings sit vacant amid rolling lawns overgrown with weeds on the 216-acre site.

The training exercises have upset Hughes and some of her neighbors, who complain that the law enforcement officers descended on the hospital grounds without warning and disrupted the quiet of their rural community in northern Prince George's County, where pick-your-own strawberry fields and weatherbeaten tobacco sheds have survived the encroachment of a modern "business park" a few miles away.

"I told them, 'The least you could have done was to let me know you're here. This is my community, not your community,' " Hughes said.

Sharon Markowich, a special education teacher at Matthew Henson Elementary School in Landover, said her roommate called one morning last week to warn her that police cars were blocking Glenn Dale Road and that Markowich should take the back way out.

"It's far enough away from me that I'm not super-concerned, but that's certainly not what I want the land to be used for," said Markowich, who lives about a quarter-mile from the hospital. "It's kind of country out here."

In light of the complaints about noise, District officials will suspend police training exercises there, according to spokesman Kathy Williams.

District police Lt. William White III said the District's "emergency response team," which handles hostage and barricade situations, had trained there about five times since March, using helicopters and blank ammunition.

Secret Service spokesman Mike Tarr confirmed that the Secret Service had held training exercises on the site four times last month.

"Occasionally for a change of scene for the training programs we like to move away from our own facility to have a different scenario and different problems," he said. The Secret Service's own training center, complete with indoor and outdoor shooting ranges and a classroom building, is in nearby Beltsville.

Tarr said that no helicopters or live ammunition were used during the Secret Service exercises but that agents "may have used some simulated explosion devices" that would have sounded like bombs. He said the Secret Service "cut back on the noise factor" once it discovered that neighbors had complained.

Two additional sessions are planned this month, Tarr said.

Prince George's County police have also trained on the property, using it two or three times last year, according to Captain Robert Phillips, commander of the Special Operations Division.

Meanwhile, not all residents were upset by the training exercises. "I was a little relieved," said Royster. "I'd rather see them up there than anyone else. I feel like it's police protection."