The factory worker, whose name has not been released, went on a shooting spree around midnight at Atlantis Plastics in Henderson following an argument with his supervisor.
After being escorted from the building, the man retrieved a hand gun and shot his supervisor before going to a break room and shooting randomly at other workers.
As he returned to the factory floor, he shot another employee before killing himself. A seventh employee was wounded and reported to be in critical condition.
Some 30 people were working the night shift at the plant when the incident took place.
Compared with other developed countries, mass shootings are not uncommon in the United States. In April 2007, the United States experienced its bloodiest mass shooting ever when an armed student killed 32 and wounded more than 20 on the Virginia Tech university campus before killing himself.
