Generally, if you have a person has a work injury, the only thing you can do is make a worker’s compensation claim against your employer.
If the injury was caused by the negligence of a third party, you may have two legal claims as a result of the one occurrence. Let me give you an example: Someone misses a stop sign in an intersection and crashes into a delivery driver, who is injured. The delivery driver would have a worker’s compensation case against his employer and a “third party” claim against the driver who missed the stop sign.