A flash mob singing the melody of Harry Dixon Loes' famous children's song This Little Light of Mine surprised the about 800 people who braved a drizzly and cold Saturday morning to witness the grand opening of the new Los Gatos Public Library.

The heartfelt performance, which improvised the key words to the song to "this library of ours, we're gonna let it shine," brought tears to many in the audience gathered in front of the facility and was led by soloist Justine Lauren and joined flash-mob style by about 40 singers.

The song's choice fit perfectly with the $18.4 million, 30,000-square-foot, two-story building's "beacon of light" architectural design theme and the town's “Jubilee Year” celebration theme of "It's Time to Shine." Los Gatos observes its 125th anniversary this year, having been incorporated Aug. 10, 1987.

The mob took place right before five lucky children helped the five members of the Los Gatos Town Council, cut a banner and featured Los Gatos Finance Director Stephen Conway playing the guitar and Andrew Ford, the chorister at Calvary Church of Los Gatos.

The program was planned by Los Gatos Councilwoman Diane McNutt, who chaired the grand-opening ceremony committee.

McNutt said the mob was part of her vision for how the library's unveiling should be. "I think that music adds memorable moments and this is one of those," she said as she paused from her greeting the hundreds that walked through the front doors of the facility located on 100 Villa Ave., next to the old Civic Center.

During the ceremony, Los Gatos Mayor Steve Rice recognized those who helped make the library a reality with donations, planning and effort and said there were more than 100 individuals who needed to be thanked.

He particularly highlighted elected officials, past and present, for their leadership; and the Friends of the Los Gatos Public Library and the town's Library Board.

"It's one thing to have a dream; it's another to turn that dream into a distinctive architectural design and real-life building that works," Rice said, thanking the architecture firm of Noll & Tam and general contractor Bogard Construction for their achievement.

Rice also thanked Los Gatos Town Manager Greg Larson and Assistant Town Manager Pamela Jacobs for helping complete the project on time and on budget.

"It's clear that it takes a town to build a library," Rice said.

Rice called the occasion a day of firsts: The first public facility built from the ground up in Los Gatos in 40 years, the community's first visit to the dazzling building and the first library in Santa Clara County to achieve Gold LEED status for features that conserve natural resources and protect the environment.

Carl Guardino, president and CEO of the Silicon Valley Leadership Group, presented a plaque to the town honoring it for being the first library in Santa Clara County's history to achieve Gold LEED building standards.

From the solar panels on its roof to the recycled concrete piers, Guardino lauded the library for being a model eco-friendly building. He also donated A Dragon on the Doorstep book to the library, which he said 7-year-old daughter Jessica had picked.

Rice also recognized Carol Hamilton, president of the Friends of the Los Gatos Public Library, for helping raise $2.1 million to pay for the library's furniture, fixtures and equipment.

Rice said supporters' generosity was impressive with some residents donating more than $10,000 and The Valley Foundation giving $500,000.

A plaque will be placed in the library's front to recognize the Friends' accomplishment.

Hamilton compared the celebration to a new grandmother, "relieved that the labor is over and ready to show off our new addition to the world and it is perfect."

Hamilton explained in 1994, the Friends established a nonprofit organization and opened a bank account named "Fund of the Future." Little did the group know that in 2012, it would help fill the new library.

Longtime Los Gatos resident Lee Pulver called the event "phenomenal" and said he was pleased with the facility's high use of technology.

"The whole concept of trying to get people to read and engage in society is tremendous," he said.

Scott Perry, wife Thao and children Andrew and Justin, ages 13 and 8, said the library was "awesome, wonderful, can't wait to start using it every day."

"The children's section is our favorite. It's so technologically advanced. The big-screen computers are great," he added.

Andrew, who attends Union Middle School, said he would probably be patronizing the new library to do his homework. "There are really good books that I like in there," he said.

"It's so spacious and everything is accessible," Scott Perry continued. He's the pastor at Holy Cross Lutheran Church in Los Gatos.

Most attendees expressed delight with the building's size, design and its use of light.

Loma Prieta Elementary School student Kylie Horn was impressed by its size. "It's big, it's big," she repeated to dad Deric Horn as they took the stairs to the second floor.

Los Gatos Coffee Roasting Company also has a place on the first floor of the new library with a concession stand called "Gatito Cafe" featuring the coffee shop’s entire espresso bar menu during library hours. "We're very honored to be here," said owner Teri Hope, who's been in town for more than 30 years.