(CNN) -- A school board in Rhode Island has voted to fire all teachers at a struggling high school, a dramatic and controversial move aimed at shoring up education in a poverty-ridden school district.

In a 5-2 vote Tuesday night, the board approved the plan by Frances Gallo, superintendent at Central Falls School District, to discharge the teachers, administrators and other personnel at Central Falls High School.

The firings -- which will be effective at the end of this school year -- came after the district said it failed to reach an agreement with the teachers' union on a plan for the teachers to spend more time with students to improve test scores.

A union spokesman told CNN the firings were "drastic" and cited a 21 percent rise in reading scores and a 3 percent hike in math scores in the past two years.

The school district said 93 people -- including the principal, three assistant principals and 77 teachers -- were fired. The teachers' union said the firings affected 74 classroom teachers plus a number of other educators such as guidance counselors and reading specialists.

Central Falls High is one of the lowest-performing schools in Rhode Island. It is in a community where median income is $22,000, census figures show.

Of the 800 students, 65 percent are Hispanic and for most of them, English is a second language. Half of the students are failing every subject, with just 55 percent skilled in reading and only 7 percent proficient in math, officials say.

In a proposal based on federal guidelines, Gallo asked teachers work a longer school day of seven hours and tutor students weekly for one hour outside of school time. She proposed teachers have lunch with students often, meet for 90 minutes every week to discuss education, and set aside two weeks during summer break for paid professional development.

A spokesman for the union said the teachers had accepted most of the changes, but just wanted to work out the compensation for the extra hours of work.

The superintendent said the two sides could not agree on a pay rate.

Under new federal requirements for school reform, low-performing schools have several options for shaping up. One is called the transformation model, which includes a series of changes that teachers just agree to adopt.

When the negotiations on those changes failed at Central Falls High, the superintendent switched to another option: the turnaround model, which means firing every single teacher at the troubled school.

Kathy May, a teacher at Central Falls High, said she's "disheartened. I feel like, after 20 years, I can see some progress beginning to be made. And I'm sad that we're not going to be around to follow that through, to push that forward."

Gallo -- who said Rhode Island law says notice must be given by March 1 -- said the problem isn't solely the fault of teachers and it wasn't her preference to make the move. She indicated that some of the teachers might be rehired.

"When we had to move from the transformation model, the next best move was the turnaround model. And that requires us to remove the teachers and rehire, of those who reapply, up to 50 percent," she said.

"This is a major move, for a very significant reason, and that being that we couldn't hone in on the assurances we needed for the transformation model."

Asked what would happen if the teachers' union accepted the original terms, Gallo said it would be "very difficult" to go back, but can't be discounted.

"And if ... as we move forward, if indeed something of that effect comes around, then I still think we have a lot of doors that could be opened."

At a community rally before the school board meeting on Tuesday, supporters of the teachers slammed the plan.

Jane Sessums, president of the Central Falls Teachers Union, said teachers have been "unfairly targeted" and scapegoated and the union will fight to have them reinstated.

"We want genuine reforms, not quick fixes that do nothing but create a wedge between teachers, our school and our community," said Sessums. She added that "teachers have agreed to numerous solutions and reforms."

George McLaughlin -- a guidance counselor who was fired along with his wife, a chemistry teacher -- told CNN that the school has been inaccurately cast as a place with low graduation rates.

"We have the most transient population in this state. Nobody comes close to us. So when they say that 50 percent of the people graduate, a very high percentage of our students leave our school. They return. They leave again. They go back to other countries," he said, noting that three times as many of the school's students are accepted to colleges now than they were five years ago.

He also knocked the superintendent, saying she "has been with us for a little more than three years."

If Gallo were willing to negotiate and listen to former Sen. Lincoln Chafee, who has offered to mediate, "maybe we could resolve this instead of causing more trauma to us."

McLaughlin said the negotiations were about job security, not pay, and said the teachers are ready to resume talks.