Hundreds of people gathered in California on Friday to protest Urban Shield, the annual expo showcasing police and military weapons and offering SWAT training in the Bay Area.

At least 23 people were arrested as protesters from a wide swath of civil and human rights organizations locked themselves to the entrance of the Alameda County Fairgrounds, where the convention is taking place from September 8-12.

Critics say the event promotes violence and police militarization, particularly in minority and low-income communities.

"The same repressive international forces backed by the U.S. to oppress people across the world are coming together to train with police forces in our local neighborhoods. Urban Shield is literally spreading war on our communities both here and in our homelands," said Nora Abedelal of the Arab Resource and Organizing Center, one of the organizations behind the protest. "We are here today to stand with all communities against the militarization of police, and to demand an end to Urban Shield."

At the time of publication, the gates at the fairgrounds were still being blocked. Elsewhere, activists marched through the streets, carrying signs and banners that read, "End the Militarization of Our Communities" and "End State Repression."

Here in solidarity with #StopUrbanShield activists from around CA @StopUrbanShield pic.twitter.com/0jHX77gDtr — SURJ Bay Area (@surjbayarea) September 9, 2016

#StopUrbanShield : Protestors shutting off the front entrance of the Alameda County Fairgrounds. Photo by Brooke A. pic.twitter.com/XXUVKMEfm2 — Ella Baker Center (@ellabakercenter) September 9, 2016

Asians for Black Lives shuts down entrance to Urban Shield this morning. #StopUrbanShield pic.twitter.com/ToDB3c7w1i — It's Going Down (@IGD_News) September 9, 2016

A petition to stop Urban Shield states, "These weapons and surveillance tools get integrated into the violence of everyday policing targeting Black, Brown, and poor communities. For instance, Black people are up to 40 times more likely to be impacted by SWAT raids than whites, clearly demonstrating the racism inherent in militarization and policing."

On Twitter, the actions are being updated with the hashtag #StopUrbanShield.