The federal government said Monday that a squadron of sharpshooters killed 20 white-tailed deer in Rock Creek Park during a three-night operation designed to trim the ranks of the animals that had become more prevalent in Northwest Washington in recent decades.

"Rock Creek Park resource management specialists, in coordination with United States Park Police and local law enforcement, worked closely with highly trained marksmen from the United States Department of Agriculture to reduce the deer population in the park," Tara Morrison, the park's superintendent, said in a statement that noted the efforts took place "without incident."

The National Park Service said the snipers, who worked at night while the park was closed and entrances were blocked by police officers, used lead-free ammunition.

"Public safety was the highest priority during this operation," Morrison said.

The park service will donate "all suitable venison" to food banks or homeless shelters in the region.

Federal officials had become increasingly concerned about the growth of the deer population in the park. They blamed the deer -- about 70 per square mile -- for eating tree seedlings, which threatened the long-term health of the surrounding forest.

Wildlife experts say the park, which doesn't allow hunting, should have 15-20 deer per square mile.

After years of study and debate, the park service approved a 25-page plan last May that allowed the reductions to move forward.

Despite the prolonged debate, the strategy that the park service chose prompted ample protest: Opponents of the plan staged a demonstration near the park on Saturday, and about 4,800 people signed an online petition decrying the tactic.

"The park service proposal is not only unprecedented, but it is unnecessary, ineffective, inefficient, inhumane and unacceptable," organizers Carol Grunewald and Jeremy Rifkin wrote.

But the park service was unmoved and proceeded, backed by a federal judge who refused to put a halt to the tactics after five people filed a lawsuit that claimed the plan would convert the park "into a killing field."

"There appears to be little dispute that a decision must be made about what to do, and people understandably have strong views about the right course," U.S. District Court Judge Robert Wilkins wrote. "But the role of this Court is not to decide that course. That is a role that Congress has entrusted to the park service."

The agency said Monday that "thinning operations" will start again in the fall.