HACKENSACK, N.J., DEC. 24 -- Kenneth Rodriguez, a chemical-plant worker, was pulled into a mixing vat and impaled on a corkscrew auger but was saved by rescuers who rushed him and the 2,500-pound vat to a hospital, authorities said today.

Rodriguez was in critical condition at Hackensack Medical Center after the accident Wednesday night. Four surgeons worked all night, until 9 a.m. today, to free him from the machinery and repair the injuries, Dr. John LoCurto Jr. said.

Rodriguez was working around the four-foot-diameter chemical mixing vat at the Napp Chemicals Inc. in Lodi when his hand became caught in its internal machinery. He was pulled inside head first, and his left arm was twisted into the screw of a 12-inch-wide, 3-foot-long auger, police said.

A second, smaller auger about 2 or 3 inches in diameter and a foot long pierced Rodgriguez's chest, doctors said.

"It's almost impossible to get caught the way he got caught," said Jim Gannon, a worker at the plant.

Unable to free Rodriguez to take him to the hospital, rescuers had plant workers free the mixing vat from its foundation with a forklift so it could be taken by moving van to the Hackensack Medical Center with Rodriguez inside.

LoCurto said rescuers made an important decision in not continuing to try to free Rodriguez once they realized he was caught inside the machine.

"Whenever you have a penetrating injury to the chest, it's important not to remove that piece until you get everything under control," he said.