When the children at Martin Luther King Jr. Elementary in Southeast Washington left school on Friday, they had no idea what would happen there before their return on Monday.

But on Saturday, 150 volunteers stormed into the empty building with the efficiency of a military platoon and got to work.

They painted the drab brown linoleum-tiled stairwells red, blue and yellow. Drew clouds on the ceiling tiles of the library. Created murals. Planted flowers in front of the school. Left inspirational messages in the bathroom stalls. Built Ikea furniture to revamp the teacher’s lounge. The list goes on.

And the volunteers completed their mission in a single afternoon.

“They are going to be so surprised and really excited,” said Angel Hunter, the principal of King Elementary, which serves about 380 students in preschool through fifth grade. “It boosts teacher and student morale.”

About 80 female veterans led the efforts in the Congress Heights neighborhood of Washington. Some of them were locals and others traveled to the District to attend the Women Veterans Summit — an annual conference that trains veterans to be leaders and activists in their communities.

The Mission Continues, a nonprofit organization that connects veterans with their communities through services, hosted the summit.

Members of the organization have volunteered for years in Congress Heights, a mostly black and low-income neighborhood.

Donating their time and resources to a neighborhood school in need was a natural fit.

“Because of our service we are accustomed to coming together to finish a mission,” said Jennifer Anthony, an Air Force veteran who lives in Missouri and completed tours in Afghanistan and Iraq. “And we’re doing that in a different capacity. Today it’s about servicing the kids in this school.”

Within a half-hour of the veterans’ arrival at the school, they scattered across the three-story building and began running down their task list. They wore blue shirts that said “Reporting for duty in your community.”

Some volunteers removed old furniture, while others quickly started building new seating and tables. One woman swiftly painted a mural of the Chesapeake Bay in the library — a request from school staff members who said the students were learning about the watershed.

The volunteers lined the multiple staircases, painting each stair a bright color so when the students walk up and down it will look like a rainbow. They even purchased a divider to install in the large cafeteria so the P.E. teacher could lead class without interrupting students who are eating lunch. The library was outfitted with new tables that have dry-erase-board tops.

“Committed partners like the Mission Continues remind us of what is possible when we are active ambassadors of service,” said Ayris Scales, the chief service office of Serve DC, which is part of the mayor’s office on volunteerism and partnerships. “Over the past four years, our city, local communities and schools have benefited from these deep investments.”

Jacqueline Clayton, a member of the Mississippi Army National Guard who is stationed at the Pentagon, said she views volunteering as an integral part of her identity as a service member.

“The passion for service doesn’t stop when we get out of the military,” she said. “It’s uplifting.”

When pupils see the finished work on Monday, the King principal said, she imagines that they will express the enthusiasm and joy that only children can. She anticipates them wanting to show her the new art and furniture in their school, pointing at and touching it all, asking her repeatedly whether she has seen the changes.

And there will be surprises for them to discover throughout the building.

When they use the restrooms, the children will find positive messages from the veterans written on sticky notes and attached to the mirrors above the sinks.

“You will achieve great things!” one says.

“You are talented,” reads another.

“There is always, always something to be thankful for,” says a message on a bright pink note.