Burd, who has been active in local theater productions, was taken to Albert Einstein Medical Center with two broken bones in his neck and a gash to his head, said Paul G. Vallas, the district's chief executive.
"They decided to wait until class had been completed, and they decided to assault the teacher outside class," Vallas said.
The students, whose names were not released, fled the high school and were later arrested, police said. Both students, who were described as special-education students, were being interviewed last night at Northwest Detectives.
The 15-year-old, a ninth grader, was in the process of being transferred to an alternative disciplinary school when the assault occurred, Gallard said. He had been transferred to such a school during the last school year.
"This is a really heinous act," Vallas said. "It was very deliberate. It was premeditated. . . . We have it on tape."
Vallas described Burd as the school's unofficial photographer, who was "much beloved" and had been a teacher there when the current principal was a student.
The school was having a fund-raiser last night for the library and Burd had been expected to attend to take photographs, Vallas said.
A teacher at the school said Burd "has worked to provide positive experiences for the students, including directing school plays, conducting a digital photography class, and taking photos for the yearbook."
Over the years, Burd's professional plays have been favorably reviewed in The Inquirer and the Philadelphia Daily News.
So far this school year, 40 students - out of a total of 1,500 - have been transferred out of Germantown High for disciplinary problems, Vallas said.
Jerry Jordan, vice president of the Philadelphia Federation of Teachers, said safety at Germantown High had been a continuing concern and indicative of a larger problem.
"This is not new," Jordan said. "It's not just Germantown High School. It's other schools as well."
Jordan said budget cuts had lessened the district's ability to provide a safe environment for students and teachers.
Lorren Davis, 16, who had Burd for a teacher, said: "He is a very nice man. He never messes with anyone."
Gallard said Burd, in an indication of his conscientiousness, called from the hospital to make sure his room had been locked.
Contact staff writer Joseph Gambardello at 215-854-2153 or jgambardello@phillynews.com.