CITY OF INDUSTRY, Calif. (KABC) — Workers at three Amazon facilities in Southern California joined thousands of others in a nationwide strike against Amazon on Thursday amid the busy holiday shipping season.

The Teamsters union said it began a strike after Amazon ignored a Dec. 15 deadline for contract negotiations.

Teamster employees left work at delivery centers in City of Industry, Palmdale and Victorville at 6 a.m. Thursday. The Teamsters union also represents workers in San Bernardino.

The strike extends to the East Coast, affecting facilities in New York, Illinois and Georgia.

The union is calling it the largest strike against the online shopping giant less than a week before Christmas.

“If your package is delayed during the holidays, you can blame Amazon’s insatiable greed. We have given Amazon a clear deadline to come to the table and do the right thing for our members. They ignored it,” said Teamsters general president Sean M. O’Brien. “These greedy executives had every chance to show decency and respect for the people who make their obscene profits possible. Instead, they pushed workers to the limit and now they are paying the price. This strike is at their expense.”

In a statement to ABC News, an Amazon spokesperson claimed that most of the strikers were not Amazon employees.

“What you see here are almost entirely outsiders – not Amazon employees or partners – and claiming otherwise is just another lie from the Teamsters. The truth is that they could not get enough support from our employees and partners and brought in outsiders. “Come and harass and intimidate our team, which is inappropriate and dangerous. We appreciate our team’s great work serving their customers and communities and remain focused on getting customers their holiday orders.

CNN Wire contributed to this report.