Authorities issued an all-clear after police investigated a bomb threat for about two hours Thursday afternoon at the City College of San Francisco, officials said.

The all-clear was given about 4:30 p.m., school spokesperson Evette Davis said. No bomb was found, no injuries were reported and the buildings were re-opened.

“Everything is OK,” Davis said.

Authorities evacuated three buildings on the school’s main campus at around 3:40 p.m. in search of reported suspicious devices, the San Francisco Police Department and a school official said.

Nothing suspicious had been found shortly before 4 p.m., Davis said. The call came in around 2:30 p.m. from an unknown individual.

“There’s been no disruption of classes beyond those buildings,” Davis said.

Officials warned people to avoid the area of 50 Phelan/Frida Kahlo Way.

⚠️AVOID THE AREA⚠️ Please avoid the area of CCSF's Ocean Campus as we investigate a potential threat. We are assisting in evacuating affected buildings and searching for any suspicious devices. Please keep the area clear for emergency responders. pic.twitter.com/35gv0FNvVy — San Francisco Police (@SFPD) October 17, 2019

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Anna Bauman is a San Francisco Chronicle staff writer. Email: anna.bauman@sfchronicle.com Twitter: @abauman2