Updated

Washington-area residents were living "in a state of fear" Monday after learning that the shooting of a 13-year-old boy at his school was the work of the same sniper who has shot seven others.

The shooting of the gunman's youngest victim yet heightened anxiety across the densely populated neighborhoods surrounding the nation's capital. Schools kept youngsters indoors at recess and lunchtime, and parents raced to pick up their children early under the watchful eyes of police.

"This community is in a state of fear," Montgomery County Executive Doug Duncan said. 

The child was shot once in the chest before the start of classes at Benjamin Tasker Middle School and was in critical but stable condition at Children's Hospital in Washington. Doctors said they were optimistic he would survive.

The sniper has shot eight people since Wednesday, killing six of them. Five died in Montgomery County within five miles of each other, and the sixth died on a Washington street. The latest attack was in neighboring Prince George's County, just north of the nation's capital.

Police say there have been no eyewitnesses and precious little to go on. They have spoken of a single sniper, but have not ruled out the possibility that more than one person is involved.

Ballistics tests found that the bullet which struck the boy was identical to those which killed some of the other victims and wounded a woman in Virginia, said Joe Riehl, an agent with the federal Bureau of Alcohol, Tobacco and Firearms.

All victims were hit by a single shot.

"All of our victims have been innocent and defenseless, but now we're stepping over the line," Montgomery County Police Chief Charles Moose said, tears streaming down his face. "Shooting a kid -- it's getting to be really, really personal now."

President Bush denounced the attacks as "cowardly and senseless acts of violence," and he promised government support to local authorities and schools.

In Monday's attack, a shot was heard and the boy slumped over, telling his aunt he thought he had been shot, Prince George's County Police Chief Gerald Wilson said. Police cars surrounded the school and officers put up crime scene tape and searched the campus.

Schools in Montgomery and Prince George's counties initiated a "code blue" alert, keeping students inside during recess and lunchtime.

Montgomery County officials asked parents to escort their children to school Tuesday and serve as safety patrol volunteers.

Sharon Healy had just sent her 12-year-old son, Brandon, off to Benjamin Tasker on his bicycle when she heard of the shooting shortly after 8 a.m. She said she ran there and pulled him out of class.

"You think you're safe, but you're only as safe as your next step," Healy said. Said her son: "I was scared."

In Lanham, Dana Buckner picked up her two children at Seabrook Elementary School as the school day came to a close. They normally ride the bus.

"I felt better having them with me," Buckner said. "I'm worried. I'm going to have to send my kids to school tomorrow."

At Benjamin Tasker, 13-year-old Othar Haskins stood outside with his mother. He said he was a friend of the wounded boy.

"He's funny, he's always around friends," Othar said, crying and leaning his head on his mother's shoulder. "He helps you out when you need it. He's a good friend."

Police and federal agents pored over maps and put together a psychological profile to hunt down the sniper, stepping up patrols and sorting through thousands of tips.

They also began to use a geographic profile submitted by investigators that uses crime locations to determine where the killer feels comfortable traveling and may live. A $150,000 reward has been posted for help in solving the attacks.

All the victims were shot in public places: the boy outside school, two at gas stations, two in parking lots, another outside a post office, another as he mowed the grass and the eighth on a street corner.

Dr. Martin Eichelberger, director of emergency trauma service at Children's Hospital, said doctors working on the boy made a special effort to find a portion of the bullet to give to police.

Eichelberger said the boy had a gunshot wound to the abdomen, which went through his chest, then into his spleen, stomach, pancreas and lung.

He said the boy's spleen was removed along with part of his stomach and pancreas, but he says those are organs a person can "live without."

Ballistics evidence also linked the Maryland slayings with the wounding of a 43-year-old woman Friday. She was shot in the back in a parking lot at a craft store in Fredericksburg, Va., 50 miles south of here, and was in fair condition Monday.

The Associated Press contributed to this report.