NEW ORLEANS — An announcement made Wednesday evening that Xavier University Preparatory School would be closing came as a shock to students, parents and alumni.

The all-girls Catholic school, at 5116 Magazine St., has been educating students for 98 years and was co-ed until 1970.

The Sisters of the Blessed Sacrament, who own the school and made the decision, issued the following statement: “The Board of Directors, the School Administration, and the Sisters of the Blessed Sacrament worked tirelessly to meet the financial challenges facing the Prep, but after reviewing the financial projections for the 2013-14 school year, the Sisters concluded that the Prep does not have a financially sustainable future.”

One grandparent who waited outside to pick up her granddaughter Thursday said she didn’t want to talk because she didn’t think the closure was really going to happen.

Another parent just lifted her hands in the air and said it was too overwhelming, and too sad, to talk about.

The Archdiocese of New Orleans issued a statement that said it was “saddened and surprised” by the sisters’ decision.

“While Xavier University Preparatory School is not owned or operated by the Archdiocese of New Orleans, we did offer financial resources to the Sisters, but the Sisters, while grateful, declined our offer,” the archdiocese’s statement said.

Emmanuel Green, a grandparent of a senior, said that the news given to families at a meeting Wednesday was a total shock and came “out of the blue.”

Kimberly Dilosa, a 1992 graduate, said she was heartbroken when she heard the news. “I got so sick to my stomach — I cried for about two hours,” Dilosa said. “The school shaped who I’ve become as a woman.”

Dilosa then immediately began an effort to galvanize alumni and other supporters to “get to the bottom of this” and to meet to explore options, such as chartering and fundraising efforts, to keep the school open.

“Even more, I’m offended,” Dilosa said. “It seems all of the sudden. There was nothing in the newsletters. The alumni didn’t have a chance to support it — if they’d given us a year in advance. ...”

On the school’s website, under the prominent banner stating “The Tradition of Excellence Continues …,” a statement release by the school said “While our hearts are heavy with this news, the academic success of our students remains our #1 priority and we are certain that for them, the best is yet to come. We remain committed to the students and families of Xavier Prep and will work with the Archdiocese of New Orleans to help all students transition to new schools, if need be.”

Waiting for her ninth-grade granddaughter, Karen Lewis said she received a letter Wednesday that listed low enrollment as one of the reasons for closures.

Lewis said she came out of retirement to help pay for tuition.

“I wanted her to finish here,” Lewis said. “She was just starting to get used to it.”

Lewis, whose father attended the school, said she started getting paperwork together to try to figure out where to enroll her granddaughter.

Perry Tillman, a 1962 graduate, credited the school with his going on to attend Xavier University on a scholarship.

A football player at Prep, Tillman said that he made lifelong friends and recently attended his 50th reunion. On Thursday, he said he was getting phone calls from all over the country asking about what was going on.

Halvan Lieteau, a 1949 graduate, described the school as an athletic powerhouse. Lieteau also went on to Xavier University on a football scholarship before attending graduate school in New York.

Though he said the nuns favored the football players, he said the emphasis was always on academics.

Lieteau said some of the “flavor went out” when the school ceased to be co-ed, and also noted that, “All the pretty girls from the 7th Ward went to Xavier Prep.”

“I feel very bad they are not able to pull the resources together stay open,” Lieteau said. “It’s difficult to have traditional institutions disappear, but there are similar situations all over the country.”

Facing modern realities, Lieteau said the decision to close was understandable from a financial standpoint.

Dilosa, who recently attended her 20-year reunion, described the atmosphere in high school as a sisterhood.

She said that the emphasis on community service led her to pursue a career as in social justice and community organizing.

“Xavier Prep brings out the best in every child that crosses the threshold,” Dilosa said.

A group of alumni plans to meet for a “citywide strategy session” at 10 a.m. Saturday at Dr. Martin Luther King Charter School at 1617 Caffin Ave.