Those at the vigil sang songs and lit candles during a photo slideshow.
Police have not said whether they believe Padgett had a specific target when he arrived at Reynolds High School in Troutdale on Tuesday morning or planned a random shooting.
Padgett was passionate about guns and had a temper, but he also seemed like a nice and normal kid, students say.
"He always talked about guns," said Kaylah Ensign, a student who had a class with Padgett and was a close friend of the victim. She said Padgett could be kind and respectful but sometimes got angry.
"He helped kids, and I never would have thought he would do that," Ensign recalled. "And he was really neat."
Freshman Daniel DeLong, 15, said he would see Padgett in the halls but did not have any classes with him.
"Honestly, he looked like a really nice kid, like somebody you'd want to have on your side," DeLong said.
Earl Milliron, a close friend of the Padgett family, said Jared planned a career in the military, was a devout Mormon and was ordained as a deacon at age 12. He was so dependable at church, Milliron said, that the bishop appointed Jared president of the deacons' quorum.
"His father never told me he was worried about Jared. And I never suspected that he had serious problems," said Milliron, 86, who has known the Padgett family for more than 25 years and belongs to the same church ward. "I refuse in my mind to believe that Jared Michael who did the shooting is the same Jared Michael I knew."
Padgett's oldest brother had served in the military in Afghanistan and the younger boy was planning the same path, Milliron said. Jared Padgett was in the Junior Reserve Officers' Training Corps program and was proud to be seen in his uniform.
Padgett's parents had separated about five years ago, and the father raised the couple's six children, Milliron said.
"I saw Jared at church every Sunday," he said. "He was very quiet, I never saw him angry, he was extremely even-tempered, he was always at the best possible behavior."
Padgett had taken the weapons used in the attack from his family home, Troutdale Police Chief Scott Anderson said.
"The weapons had been secured, but he defeated the security measures," the chief said.