Fortunato “Fred” Rubino, the former longtime principal of I.S. 318 Eugenio Maria de Hostos in Williamsburg, who was recently appointed the superintendent of Brooklyn’s District 14, died Monday morning.

The death was sudden, said Brian Leavy-DeVale, the principal of nearby P.S. 257 John F. Hylan and a friend and former colleague of Mr. Rubino’s at I.S. 318. After suffering an attack, he was taken to Woodhull Medical Center, where he could not be revived. He was in his mid-50s, said Mr. Leavy-DeVale, who was with the family at the hospital.

At the District 14 offices, Shakira Maldonado, Mr. Rubino's administrative assistant, said "he was a great man." She also said: "I think everyone's just a little shocked.''

Born into a big Italian family in Williamsburg, Mr. Rubino lived in Greenpoint with his wife, Leanne, and a son, Joseph, according to Mr. Leavy-DeVale; another son, Rocco, plays professional basketball in Italy. He started as a special education education teacher at I.S. 318 before working his way up to principal, and he served for about a decade before being appointed superintendent earlier this year.

Ernest Logan, the president of the principal's union, the Council of School Supervisors and Administrators, described Mr. Rubino as "a wonderful, wonderful man."

"He was able to reach our adolescents in their middle years, which is always a difficulty," he said. I.S. 318, known for its championship-winning chess team, is "one of the best-run middle schools in this city," Mr. Logan said.

Mr. Rubino was widely respected in Williamsburg, Mr. Leavy-DeVale said, where he regularly played basketball, as well as the banjo and the guitar.

“As an educator and as a father, he was the best of the best,” he added. “They say God takes ‘em young, and this was a case in point.”

As a principal, he was a fierce advocate for his teachers in the face of the city’s effectiveness ratings.

Knowing that value-added scores were being used to determine whether a teacher got tenure, Mr. Rubino decided to introduce his own evidence of quality teaching to help six of his teachers who were up for tenure, according to Gotham Schools.

Mr. Rubino videotaped each of the teachers during a lesson, and sent the videos to the superintendent to consider, because he believed the teachers' classroom work was at least as important as the scores.

“If you’re going to say to me, ‘Well, I don’t want to tenure that teacher,’ then you’re going to have to look at that lesson and say this person can’t teach,” he told Gotham.

Mr. Leavy-DeVale said Mr. Rubino was “overjoyed” to be appointed superintendent, and at a party last month, more than 200 people showed up to honor him. Several people at the party spoke about how much he had influenced their lives.

“Everyone really let him know how much they cared about him,” Mr. Leavy-DeVale said. “You never want to die, but at least he had that moment.”