(KRON) — A shooting occurred on campus at Skyline High School in Oakland while students were in class Tuesday, investigators said. Oakland Police Department officers swarmed the school, detained four suspects, and arrested two.

No one was injured, OPD Captain James Bassett said. The shooting happened at 11:30 a.m. and the school was placed on lockdown. “Evidence of a shooting was recovered, including a handgun,” Bassett said. “Thankfully there were no reported injuries.”

Parents received a text message from school officials just before 1 p.m. confirming that all students and staff were safe.

Police and school district officials declined to release any further details about the arrested suspects. They declined to talk about what possibly led up to the violence.

Oakland Unified School District spokesman John Sasaki told reporters that the school followed emergency protocols to keep students safe. “This has been happening far too much in our community, far too much in our world right now, and it needs to stop. Stop engaging in violence in all its forms. Whatever the conflict you might have, whether it’s in the city, or anywhere else, it’s not worth the consequences. Please stop.”

Skyline High School is located at 12250 Skyline Boulevard. Sasaki said there are no metal detectors on campus. Skyline will be closed on Wednesday as police investigate and the school prepares its students to return.

This is a developing story. Check back for updates.