PORTLAND, Ore. >> An 18-year-old man arrested Sunday is the second of three people believed to be involved in a shooting outside an alternative Portland high school, police said.

Marquel Dugas, 18, was arrested on a probation violation and lodged into jail Sunday afternoon.

Police said they are working to identify a third person connected with Friday’s shooting near Rosemary Anderson High School.

One of three people hospitalized has been released. Taylor Zimmers, 16, remains hospitalized in serious condition, while David Jackson-Liday, 20, was in fair condition. Labraye Franklin, 17, was released from the hospital on Saturday. A fourth person, a 17-year-old girl, was grazed by a bullet and treated at the scene.

Police arrested a 22-year-old man in connection with the shooting early Saturday. Lonzo Murphy was charged with a parole violation and could face additional charges. Police said he’s a “person of interest” in an incident they believe was related to gang activity.

Murphy was pulled over early Saturday, and police found a handgun in the vehicle though it’s unclear whether that gun was used in the shooting.

Police have said Murphy and the two male victims had ties to a gang.

On Sunday, Zach McKay was among several dozen people who attended an open house at the school, the Oregonian reported.

“This is my family. It’s important to talk about it,” McKay, who graduated from the school in 2010. “Good to get it out sooner than later.”

School President Joe McFerrin told the newspaper that community agencies and trauma experts will be available to students on Monday.

Police said officers on Monday will also provide extra patrols of the school, as well as a nearby high school and community college in the city’s north end.