One of the Michael Brown memorials in Ferguson, Mo. (Scott Olson/Getty Images)

A tree dedicated to Michael Brown over the weekend in Ferguson, Mo., was damaged within a day, while a plaque accompanying the tree was stolen, according to the city.

This tree, a sapling, was purchased by the Black Caucus of the American Library Association in Chicago. It was dedicated in January-Wabash Memorial Park on Saturday to Michael Brown, the unarmed 18-year-old shot and killed by a white police officer in the summer.

Another tree in the park, this one purchased by a resident in honor of a dead pet, was also damaged over the weekend, the city of Ferguson said in a statement Monday. The plaque at the base of that tree was stolen as well.

While police believe the trees were broken and the plaques stolen overnight on Saturday, it could have happened any time before an officer patrolling the area noticed it Sunday, the city said.

“Officers canvassed the area talking to anyone who might have seen or heard anything related to the incident,” the city’s statement said. “No witnesses were located, and at this time police have no leads. An investigation into the incident is ongoing, and the City of Ferguson is replacing the trees today.”

New plaques will be in place later this week, the city said.

Ferguson has erupted in heated protests multiple times since Brown was killed by Darren Wilson, a police officer, in the summer. A grand jury ultimately decided not to indict Wilson last year, while the Justice Department announced last month that after a lengthy review, they found evidence that corroborated Wilson’s account and declined to pursue federal civil rights charges.

This is at least the third time that a memorial to Brown was destroyed. In September, a memorial on Canfield Drive, not far from where Brown was killed, was destroyed by a fire. A car hit and destroyed a memorial in December.