SHAKOPEE, Minn. — William Stolz, an Amazon fulfillment center employee, enjoys some parts of his job.

But Monday afternoon — the first day of Amazon's yearly sales event, Prime Day — he and dozens of his coworkers walked out in order to draw attention to what they say are ongoing issues with working conditions and expectations at the company's warehouses.

"You know, there's a lot about this job that I really like," Stolz said in an interview Sunday. "But they've got to do something to change just some of the basic problems with these working conditions."

The strike is timed to coincide with the company's biggest sale of the year, which this year stretches to two days of deals on thousands of items. The resulting wave of orders means a particularly grueling time for workers at Amazon's fulfillment center, where they help sort and ship packages.

The working conditions in Amazon's warehouses along with the salaries of Amazon's many workers there — the company employs more than 250,000 full-time employees as well as part-time workers in its fulfillment centers around the world — have been the subject of criticism from labor activists as well as some of the company's employees.

In response, Amazon raised its minimum wage to $15 an hour and has said that it has invested in improving working conditions.

An Amazon spokesperson said in an email on Monday that company critics were taking advantage of Prime Day.

"Events like Prime Day have become an opportunity for our critics, including unions, to raise awareness for their cause, in this case, increased membership dues," the spokespersons aid. "These groups are conjuring misinformation to work in their favor, when in fact we already offer the things they purport to be their cause — industry leading pay, benefits, and a safe workplace for our employees. We can only conclude that the people who plan to attend the event on Monday are simply not informed. If these groups — unions and the politicians they rally to their cause — really want to help the American worker, we encourage them to focus their energy on passing legislation for an increase in the federal minimum wage, because $7.25 is too low."

But Stolz and other workers said the strike is meant to get the company's attention and engage them in a broader discussion about the pace that is expected of its warehouse employees.

"We want to send a powerful message to Amazon that they really need to have these be safe, reliable jobs," Stolz said. "You know, do something about the speeds that we have to work."

Stolz works in a warehouse in Shakopee, Minnesota, just outside of Minneapolis. That center has become a hotbed of worker activism including organizing by East African Muslim immigrants who have protested working conditions including the relaxation of worker quotas during Ramadan, when many Muslims fast.

The planned strike has already caught the attention of labor groups and some politicians. Democratic presidential candidates Elizabeth Warren and Bernie Sanders both offered public support on social media for the strike.

"I fully support Amazon workers' Prime Day strike," Warren said in a tweet. "Their fight for safe and reliable jobs is another reminder that we must come together to hold big corporations accountable."

"I stand in solidarity with the courageous Amazon workers engaging in a work stoppage against unconscionable working conditions in their warehouses," Sanders tweeted. "It is not too much to ask that a company owned by the wealthiest person in the world treat its workers with dignity and respect."

I fully support Amazon workers' Prime Day strike. Their fight for safe and reliable jobs is another reminder that we must come together to hold big corporations accountable. https://t.co/ZkDDt9zeHv — Elizabeth Warren (@ewarren) July 15, 2019

Tyler Hamilton, who also works at the Shakopee warehouse, said he also hoped that consumers would remember that there were people behind the packages that show up at their doors, often less than 48 hours after placing an order.

"We are the faces behind the boxes," Hamilton said. "The little smiley face that comes with every package, not everyone in there smiles all the time. It can be rough sometimes. And, you should think about that when you order it."