Jared Boger, 17, was stabbed in the chest, the blade plunging nearly to his spine and missing his heart by fractions of an inch. He remained in critical condition Saturday at UPMC Presbyterian Hospital.
"He is writing and is able to nod and answer questions," said UPMC spokeswoman Cyndy McGrath, who did not mention Boger by name.
Boger is among five students still hospitalized in the wake of Wednesday's attack at Franklin Regional High School. One 15-year-old boy and two 16-year-olds were listed in critical condition in the intensive care unit of Forbes Regional Hospital on Saturday, while a 14-year-old student was listed in fair condition at Children's Hospital of Pittsburgh of UPMC.
Alex Hribal, 16, faces four counts of attempted homicide and 21 counts of aggravated assault in the rampage that injured 21 students and a security guard. Police and Hribal's lawyer have said they don't yet have a motive.
Boger's brother, Carter Boger, told WPXI-TV via Twitter: "Right when Jared woke up, he wrote, 'It's going to b OK, mom. I love u' and got teary eyed."
Dr. Louis Alarcon, medical director of trauma surgery at UPMC Presbyterian, said Friday the teenager's prognosis is "very good ... but there are a lot of hurdles before he comes off the ventilator, comes out of the ICU and leaves the hospital. We don't anticipate problems, but we're being vigilant."
It's not clear when the high school will reopen. Officials hoped it would be ready by Monday, but a restoration company won't be finished with its work by then. Dan Stevens, spokesman for the Westmoreland County Department of Public Safety, said some students should be able to return by early in the week and others later.
"It's important that the school looks the way it did Tuesday," the day before the attacks, he told the Pittsburgh Post-Gazette.