Updated at 10:21 a.m. ET
CHARDON, Ohio - A student wounded in a deadly school shooting has been declared brain dead, authorities said Tuesday, a day after one student was killed and three others injured when a teenager opened fire in the cafeteria at a suburban Cleveland high school.
The Cuyahoga County Medical Examiner's Office received the word about Russell King Jr. just before 1 a.m. Tuesday, office administrator Hugh Shannon said in a statement. It was unclear whether King remained on life support; the statement referred to him as both deceased and brain dead.
"The cause and manner of death of this case are under on-going investigation and will be released upon completion," Shannon said in a statement. A spokeswoman at MetroHealth System said Tuesday morning that no information on his condition was available.
King, 17, was one of five students injured when a suspect identified by a family lawyer as TJ Lane began shooting at Chardon High School Monday morning. King was studying alternative energy at nearby Auburn Career Center and like the others who were shot was waiting for a bus for his daily 15-minute ride to the center. Student Daniel Parmertor died hours after the shooting.
On Tuesday morning, a third student, Demetrious Hewlin, was listed in critical condition, according to a hospital spokeswoman.
Law enforcement sources told CBS News that Lane -- who says he was a victim of bullying -- warned his friends about his plans two days in advance. Sources said the suspect is cooperating with authorities. He is scheduled for an appearance in court Tuesday afternoon.
According to statistics from the U.S. Secret Service, which started compiling data on school shootings after the attack at Columbine High School in 1999, at least one other person had some prior knowledge of an attacker's plan in 81 percent of incidents. In 59 percent of incidents, more than one other person had some prior knowledge.
Of those incidents where another person knew about the attack in advance, 93 percent of those people were the attacker's friend, schoolmate or sibling.
A student who saw the attack up close said it appeared that the gunman targeted a group of students sitting together and that the one who was killed was gunned down while trying to duck under the cafeteria table.
Lane's family is mourning "this terrible loss for their community," attorney Robert Farinacci said in a statement.
FBI officials would not comment on a motive. And Police Chief Tim McKenna said authorities "have a lot of homework to do yet" in their investigation of the shooting, which sent students screaming through the halls at the start of the school day at 1,100-student Chardon High.
An education official said the suspected shooter is a Lake Academy student, not a student at Chardon High. Brian Bontempo declined to answer any questions about the student. Bontempo is the superintendent of the Lake County Educational Service Center, which operates the academy.
The alternative school in Willoughby serves 7th through 12th grades. Students may have been referred to the school because of academic or behavioral problems.
The FBI said the suspect was arrested near his car a half-mile from Chardon. He was not immediately charged.
Teachers locked down their classrooms as they had been trained to do during drills, and students took cover as they waited for the all-clear in this town of 5,100 people, 30 miles from Cleveland. One teacher was said to have dragged a wounded student into his classroom to protect him. Another chased the gunman out of the building, police said.
Fifteen-year-old Danny Komertz, who witnessed the shooting, said Lane was known as an outcast who had apparently been bullied. But others disputed that.
"Even though he was quiet, he still had friends," said Tyler Lillash, 16. "He was not bullied."
Farinacci, representing Lane and his family, told WKYC-TV that Lane "pretty much sticks to himself but does have some friends and has never been in trouble over anything that we know about."
Long before official word came of the attack, parents learned of the bloodshed from students via text message and cellphone and thronged the streets around the school, anxiously awaiting word on their children.
"I looked up and this kid was pointing a gun about 10 feet away from me to a group of four kids sitting at a table," Komertz said. He said the gunman fired two shots quickly, and students scrambled for safety. One of them was "trying to get underneath the table, trying to hide, protecting his face."
Slain student Daniel Parmertor was an aspiring computer repairman who was waiting in the cafeteria for the bus for his daily 15-minute ride to a vocational school. His teacher at the Auburn Career School had no idea why Parmertor, "a very good young man, very quiet," had been targeted, said Auburn superintendent Maggie Lynch.