Surveillance video provided by the executive director of the monument shows several people making their way up the historic structure at around 2:40 a.m.
Somehow during the incident, a bronze piece of the monument came off, falling to the ground. The piece, weighing 10 to 15 pounds, is a screw mechanism that raises and lowers the cannon on the statue.
"I actually have an ancestor whose name is on this wall, Samuel Ruple. He was actually killed in 1863 at the Battle of Stone's River, so for me this is a very personal monument, and to see somebody come in and desecrate a war memorial is very upsetting to me as an individual," said Tim Daley, the executive director of the monument.
The Soldiers and Sailors Monument honors the 9,000 people of Cuyahoga County who served in the Civil War. Their names are on the structure as well.
The monument didn't open until 10 a.m. Sunday, said Daley, and a member of the public discovered the damage.
Daley said he is disgusted that anyone would mistreat the monument, and he hopes the surveillance video will help catch whoever is responsible.
The suspects also appeared to be taking their own photos and videos, he said.
The Cleveland Police Department responded but turned the investigation over to the Cuyahoga County Sheriff's Office because the monument is on county property.
Daley said whoever vandalized the monument will face a felony under federal law. He said officials intend on pressing charges.
Daley said there has been vandalism at the monument before in the form of graffiti. Several years ago, he added, some of the swords were broken off the statue.
People visiting the monument Sunday couldn't believe anyone could do something so senseless.
"That's disrespectful. I live in Detroit and things happen there. You don't want these things to happen," said Sherry Briske, of Detroit.
Daley could not say how much it would cost to fix the monument.
Anyone with information on the vandalism, or anyone who may see videos or photos taken of the act is asked to call monument officials at 216-621-3710.