Another school shooting, this one probably gang-related, wounded one student Tuesday morning at Ridgway High School in Santa Rosa north of San Francisco.

Santa Rosa Police Department (SRPD) arrested the suspected 17 year-old gunman -- a student at the school -- after he shot a 16 year-old boy twice in the upper body near the intersection of Ridgway Avenue and Morgan Street (outside of the high school) at 8:56 a.m. Police said there were many witnesses to the shooting. The victim is in stable condition at a local trauma center.

Local TV stations aired video showing the suspect being led away in handcuffs even as students continued evacuating the high school, which has more than 10,000 students and employees.

SRPD said the suspected gunman returned to class Tuesday after the shooting. SRPD Captain John Cregan said the shooting took place after an argument between the gunman and the victim. He said investigators believe the suspect hid the pistol in someone else's backpack and this unsuspecting person took it off-campus.

"We have no evidence the student who left with the backpack knew what they had (in the backpack)," said Capt. Cregan.

He said SRPD detectives are trying to determine if the shooting was gang-related. The incident triggered an hours-long lockdown of the complex consisting of three schools in Santa Rosa. SRPD and the FBI lifted the lockdown around 11:30 a.m. after a "thorough sweep" of the schools.

“There is no evidence that the weapon is on campus,” tweeted SRPD. “The suspect is in custody & there is no threat,”

School district officials tweeted "students are safe."

Worried parents told media of their panic at getting text messages from their children and not knowing if they were safe. One bemoaned school shootings as a new normal where children are the main victims.

Ridgway High School is part of a huge complex that also includes Santa Rosa High School, Santa Rosa Junior College, school district offices and athletic fields. Colorado school shooting A woman walks out of the Recreation Center at Northridge with her son after at least seven students were injured during a shooting at STEM School Highlands Ranch on May 7, 2019 in Highlands Ranch, Colorado. Photo: Michael Ciaglo/Getty Images