San Francisco Police walk by the site of a shooting outside the June Jordan School for Equity and City Arts and Technology High School, which share a campus, in San Francisco, Calif., Tuesday, Oct. 18, 2016. Several teenage students were shot in the shared parking lot of the two San Francisco high schools Tuesday, and one of the students is in critical condition, authorities said. (Scott Strazzante/San Francisco Chronicle via AP)

SAN FRANCISCO - Students at two San Francisco schools where classmates were shot the previous day walked arm-in-arm as they exited classes Wednesday and called for an end to violence.

The expressions of sadness and resolve came after classes resumed at the June Jordan School for Equity and the City Arts and Technology High School with extra security in place as police searched for suspects in a shooting a day earlier that wounded four students, leaving one girl in critical condition.

The shootings outside the schools happened as students were being let out for the day Tuesday from the schools, creating a chaotic scene on the shared campus.

On Wednesday, some students wiped away tears as they recounted the scene from a day earlier.

Devianna Lucero, a 15-year-old sophomore, said she heard five or six loud bangs as she exited school Tuesday and at first thought nothing of it. Then chaos erupted.

"At first, I didn't believe they were gun shots. I thought someone was banging on the wall," she said. "Then everyone was screaming and running to the classrooms."

Flowers were strewn Wednesday in the outdoor parking lot where the shooting occurred, along with messages scrawled in chalk that said: "No More Violence" and "All Lives Matter."

Police said they were searching for four suspects tied to the shooting but have not said how many suspects opened fire, hitting one female student believed to have been targeted and three others.

Jessica Huang, a co-director at the June Jordan school, said the group that staged the attack were outsiders who were not members of the school. She said the wounded female student underwent a successful surgery and the other three students had been released from the hospital. All are age 15.

"It was terrifying," Fernando Rodriguez, a 16-year-old junior, told The San Francisco Chronicle (http://bit.ly/2esbbya). "We walk into this school every day, every morning, and to hear gunshots like that — just scary."

Teachers gathered students together and herded them into classrooms. The schools were locked down, and Rodriguez said he stayed inside a classroom with dozens of other students and a teacher with the door bolted shut for about 30 minutes.

Police searched both schools to determine that there was no shooter inside. Rodriguez said students and teachers were later told that the shooting had happened outside and that it was safe to leave.

Counsellors were on hand Wednesday at the schools for students and security was increased, school officials said.

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Information from: San Francisco Chronicle, http://www.sfgate.com

News from © The Associated Press, 2016