Animal rights protesters project secret-recorded video of pigs on a San Francisco Costco

Costco in San Francisco was the target of animal rights protests on Wednesday. 

The group Direct Action Everywhere projected secretly-recorded video of pigs being rendered unconscious before slaughter in chambers filled with carbon dioxide gas. 

The activist group said the footage was taken at a facility in Southern California that belongs to Costco supplier Smithfield Foods. 

About two-dozen protesters held signs to draw attention to the practice. They said the pigs suffer for several minutes before they die. 

"I don't think it's humane. Veterinarians don't think it's humane. Ultimately at the end of the day, these are individuals who want to live. So, whether we're killing them in gas chambers or with a bolt gun to the head, there is no humane way to kill animals who do not want to die," said Almira Tanner from Direct Action Everywhere. 

A group of 10 veterinarians also released a letter saying the practice may be in violation of California Humane slaughter laws, in a statement to Wired magazine. 

Smithfield said it, "Strictly follows approved laws, regulations and best practices for humane animal stunning, prior to harvest." 

SEE ALSO: Last swan of San Francisco's Palace of Fine Arts dies