President Donald Trump’s offer to most federal employees to resign now and be paid through September stunned the workers who received it — angering some, confusing many and raising questions about whether the offer is even legal.

On Thursday, as their agency worked to investigate a catastrophic plane crash between an American Airlines jet and an Army helicopter outside of Washington, employees of the Federal Aviation Administration were reportedly among government workers who got an email encouraging them to quit and find a “higher productivity” job.