Amazon has responded swiftly to the impromptu strike at its unionized Staten Island warehouse. The company and workers have confirmed to CNN that about 50 workers were suspended with pay at JFK8 after they occupied the human resources office and refused to work in allegedly unsafe conditions following a ship dock fire. One of the workers, Connor Spence, said the suspension would continue while Amazon investigated the work stoppage.

We’ve asked Amazon for comment. In a statement to CNN, a spokesperson said there was a “small fire” in a cardboard compactor, and that it asked night shift workers (including those in the protest) to report to their usual shifts after firefighters said the warehouse was safe. The “vast majority” of workers complied, Amazon said. Day shift team members were sent home with pay. 

The suspensions won’t help ease the conflict between Amazon and workers at JFK8, the company’s only unionized warehouse. In May, Amazon fired several senior managers in a move that employees claimed was retaliation for labor organization efforts. There’s also broader tension across the company. Staff at multiple American warehouses have pushed for unionization (albeit with limited success), while Amazon has been accused of using anti-union tactics.

The affected staffers won’t necessarily lose their jobs. However, it signals that Amazon isn’t keen to tolerate labor disruptions even with a union present.