The sniper's words, when Montgomery County Police Chief Charles A. Moose announced them late yesterday afternoon, froze people in place: Your children are not safe anywhere at any time. They sent chills through parents and school officials who are charged with keeping young ones safe from harm.

Many school superintendents in the Washington area said they were not told of the letter's contents in advance but were warned in a general way that the sniper planned to target children. And that, many said, is the assumption they had been operating under since the shootings began -- particularly after a 13-year-old boy was wounded outside his Bowie middle school Oct. 7.

"We have always taken very seriously every day the level of threat to our children," said Montgomery County Superintendent Jerry D. Weast. "We have always consistently shut down outdoor activities. We have consistently, unfortunately, called off school activities. And we have consistently done everything we can to keep children safe."

Public schools throughout the region are expected to open on time this morning. Montgomery County schools will be under Code Blue restrictions, with all outdoor and after-school activities canceled and children kept inside locked buildings with the blinds drawn. In the District, bus service for about 3,800 special education students in public schools will be canceled today.

Yesterday, as a man who may well be the sniper's 13th victim -- and 10th fatality -- lay bleeding not far from several schools in the Aspen Hill neighborhood, Montgomery's public schools went into a Code Blue lockdown. Children woke to the harsh chop of FBI helicopters flushing the woods nearby, and, as a police dragnet sought to seal off any escape, many children and teachers were caught for hours in a massive morning traffic tie-up.

With many students and employees arriving hours late or not at all, several area private schools, including five Catholic schools in Montgomery County, decided to close for the day. A number of nearby public schools were practically empty, with attendance falling as low as 10 percent at two elementary schools not far from the shooting.

The contents of the sniper's missive and how schools should respond to it were first discussed at a meeting that Montgomery County Executive Douglas M. Duncan (D) hastily called Monday night with representatives from city and county governments in the region. The officials knew that schools in the Richmond area were kept closed Monday and yesterday -- they will reopen today -- after the Saturday sniper attack outside the Ponderosa Steakhouse in Ashland, Va. Was that the right approach?

"The consensus was [that the letter's warning] was not a direct threat to school kids or to schools," said a source familiar with the discussion.

When the meeting broke up at 10:15 p.m., Duncan called Weast. "We told him what he needed to know in order to make an informed decision," the source said. "The relevant passage was made clear."

Weast confirmed that he was not given specifics. "Law enforcement are working very closely with us on the threat assessment, what we need to be cautious about," he said. "I don't get evidence shared with me."

Fairfax County Superintendent Daniel A. Domenech was not given the exact wording, either.

"I didn't" tell him, said Fairfax County Executive Anthony H. Griffin, who attended the Monday meeting. "Not the letter. Not the details. That was being kept secret for obvious reasons."

Domenech said he believes he received the best information officials had at the time. He declined to say more. "We are trying to stay out of the media as much as possible," he said.

Similarly, superintendents in Prince George's, Prince William, Loudoun and Fauquier counties and other districts said they were unaware of the sniper's specific threat to children. Yet they were hardly surprised and said it would not cause them to alter the precautions they are already taking.

"I don't think it surprised me because he had actually wounded one of our students," said Prince George's schools chief Iris T. Metts. "It was very obvious that he threatened children."

Across the region, many superintendents have continued to ban outdoor activities and canceled field trips. Many said they are trying to react cautiously in an unpredictable and lethal situation, while taking care not to overreact and further fray tense nerves.

For example, Fairfax County sports teams traveled to what were considered safer playing fields in Richmond over the weekend. One football team stopped to have dinner on the way home -- at the Ponderosa Steakhouse.

Patricia Weitzel-O'Neill, superintendent of the more than 100 schools in the Archdiocese of Washington, said police officials had not informed her of the threat before Moose's news conference. Nor, she said, was the warning discussed by the region's superintendents during a conference call they had Monday morning.

"You know, everybody is stymied by this," Weitzel-O'Neill said. "You have so many people on a conference call, and no one has the answer. It's so frustrating."

For many officials, the thought of closing down schools is frightening. Gov. Parris N. Glendening (D) issued a strong call yesterday to keep schools open. Said Montgomery school board member Nancy J. King (Upcounty): "We don't want parents going off to work and leaving kids at home or just hanging around. That could leave them more exposed."

And once you close, when do you reopen? And on what grounds?

Still, some parents across the region were angry that they hadn't been told of the sniper's chilling words before Moose revealed them.

The first time Montgomery County school board Vice President Patricia O'Neill (Bethesda-Chevy Chase) heard of the sniper's threat was yesterday morning, listening to the news on the radio. "I would have liked to have known. This sends a chill up my spine," she said. "Safety of the children is paramount. And every parent needs the information to make the best decision for their own child."

John O'Grady, who lives in what he calls the "target zone" in central Montgomery County, where nine people have been shot, said he was apoplectic that he didn't know of the sniper's letter. He kept his grandchildren home with him yesterday and plans to keep them home for the foreseeable future.

"There's no reason why you should take your children and dress them up in a bull's-eye and send them off to school. This guy issued a challenge," said O'Grady, who wants area schools to close indefinitely.

Laura Hinton, mother of four children in Loudoun County, said she was late picking up her 15-year-old daughter from high school yesterday, leaving her daughter to wait outside. "Had I known about this, you can bet she would not have been waiting outside that school for me," she said. "This bothers me. I don't see how it could have impeded their investigation to tell people, and to keep parents in the dark is just wrong."

The sniper's note has left Denise Simmons in a quandary. "I just don't know what to do," she said, wrestling with whether to send her son to school at Watkins Elementary in Southeast Washington. "They say our children aren't safe anywhere, and I believe it."

Some Montgomery County parents near the scene of the sniper attack opted yesterday to keep their children home. One parent kept his four children home watching movies. "They're home and they're safe," he said, speaking on condition of anonymity for fear of becoming a target for the sniper.

And for those who did venture out, the terrifying day became even more so when staff members at Strathmore Elementary School -- near an open field, woods and cemetery, not far from where yesterday's shooting occurred -- thought they heard gunshots shortly after noon.

Police rushed in, and an FBI helicopter searched the woods. Strathmore and Bel Pre elementary schools, with less than 10 percent of their normal school population yesterday, went into Code Red, the highest state of security alert. Students and staff members immediately froze in place and got out of the line of sight of windows and doors. For many, that meant lying down on the floor or crouching under desks.

No student was to talk, though frantic staff at Bel Pre, where for three weeks the windows have been covered with black paper, could whisper.

Once law enforcement found nothing suspicious in the woods -- and searched a nearby white box truck whose owner willingly offered his keys -- the schools went back to Code Blue, a restrictive status that has become all too familiar to students in recent weeks.

LaTonya Pressley had been bravely trying to continue with life as normal for herself and her two daughters. But with Moose's unveiling of the sniper's haunting words, she's not so sure.

"It makes it much worse," said Pressley, while picking up her 7-year-old from Stevens Elementary School on 21st Street NW yesterday evening. "What has my innocent child done to anyone to cause him to want to kill her or threaten her?"

Strathmore Elementary School students head home after enduring a gunfire scare. At right, Harmony Hills Elementary School secretary Ada Miranda tapes a sign to the front door with instructions for parents taking children home early. Half the students were absent yesterday after the shooting nearby.