An employee was injured at work. What do I do?

Five steps in order: (1) get the employee medical attention immediately — call 911 if it's serious; (2) document the incident (witnesses, time, location, mechanism) as soon as it's stable; (3) report the claim to the carrier and the WCB within the required windows (in NY, employees must report within 30 days, employers within 10 days of becoming aware); (4) provide the employee with the required forms (Form C-3 and the employee's rights notice) and direct them to a WCB-authorized provider where required; (5) cooperate with the carrier's claims investigation. Don't delay reporting on the theory that the injury "isn't that bad" — late reports make claims more expensive and harder to defend.