We Build the Wall, a group founded by Air Force veteran Brian Kolfage, published a post on social media on Monday, announcing that it has started the construction of a half-mile stretch of wall on private property.
"Buckle up, we're just getting started!" the group wrote in a Facebook post, while Kolfage has published a video of what was described as construction work.
The campaign has managed to gather more than $20 million in donations, while their wall will cost an estimated $6 million to $8 million.
During the fundraising campaign, some donors wondered why there were no construction works despite millions of dollars being donated; however, the campaigners said that they had to keep their plans secret to protect the project.
"Remember powerful people want to stop our progress, so to not tip anyone off while we are radio silent!" Kolfage wrote in a Facebook post.