Rescuers flew four critically wounded people to two area hospitals, according to air rescue spokeswoman Karine Hoerhager.
The situation is under control, said Lucerne county police spokesman Urs Wigger, and officers have cordoned off a wide area around the factory.
The incident took place at 9:00 a.m. local (3:00 a.m. ET) at the offices of Kronospan, a manufacturer of wood products in the town of Menznau outside of Lucerne.
The factory employs 410 people, according to local media, and has had to cut production due to a reduction in the wood harvest.