Beer cans and rocks were thrown at the officers when they responded to a car-pedestrian accident in the area around midnight, according to a news release from the city and university.
As many as 200 people - many apparently WSU students - were at a party in a rental house at the time.
Authorities were unsure what prompted the violence.
"It was a spontaneous event at a party house," Pullman Police Chief Ted Weatherly said.
The confrontation with a law enforcement team of about 100 officers attracted several hundred onlookers, and a few couches and mattresses were set fire in the street, authorities said.
Police used water hoses and small amounts of tear gas and smoke in a failed attempt to disperse the crowd, which approached campus as the confrontation dragged on, authorities said.
Officers had planned to use more tear gas, but the crowd eventually dispersed on its own about five hours after the disturbance started, authorities said.
A state National Guard contingent was placed on alert, but no National Guard members were sent to the scene.
City police were assisted by officers from the campus force, the Washington State Patrol, city and WSU fire departments and police and sheriff's departments from neighboring communities.
Most of the 23 officers who were taken to Pullman Memorial Hospital were treated for minor cuts and bruises and released, WSU spokeswoman Barbara Petura said. About four officers were more seriously injured, with one suffering a broken ankle and another a sprained thumb.
Four students were treated for minor injuries at the hospital and released, Petura said.
Damage from the disturbance included broken windows in three off-campus businesses and broken car windshields, Weatherly said. A Washington State Patrol cruiser and a fire truck were among the damaged vehicles.
Three people involved in the confrontation were arrested, police said.
Police planned to review video footage and still photos of the confrontation, Weatherly said. More arrests were expected.
WSU President Sam Smith wrote an open letter to the campus community in response to the violence.
Smith said he was upset that "an isolated incident involving students can portray the WSU community in such a negative light.
"WSU-Pullman has 17,000 students; only a small percentage of those students were involved" in the confrontation, he said.
The confrontation occurred as students prepared for final exams, which begin this week.