Emergency crews responded to a fire in the wooded area at the north end of Wallace Marine Park on Wednesday afternoon, officials said.
The fire was under control, but the road to the north section of the park leading to the softball fields remained closed, Salem Police said.
Police were patrolling the West Salem park to alert users and asked the public to avoid the area until further notice.
Wallace Marine Park covers 114 acres on the west side of the Willamette River. The main entrance off Glen Creek Road NW remained open, as did access to the boat ramps.
The north end of the park has a history of homeless encampments.
The fire started at around noon, officials said. A large plume of smoke could be seen miles away from south Salem. An hour later, the smell of smoke permeated downtown.
The fire drew a heavy emergency response, with four Salem Fire Department engines and eight Salem Police Department patrol cars. Salem Police deployed a drone while crews continued mopping up at the scene.