General Motors Corporation announced an extraordinary recall April 5 of its new midsize sport-utility vehicles, asking owners to park their trucks and wait for them to be towed back to dealers to fix a potentially dangerous steering problem. GM dealers were asked to immediately contact the 6,000 owners of 2002 Chevrolet TrailBlazers, GMC Envoys and Oldsmobile Bravadas. The dealers were instructed to arrange to have the SUVs towed, and not to ask the owners to drive them back for repairs. "Along with NADA, the nation's new-car dealers applaud General Motors' swift, preemptive action to recall and repair these vehicles," said William A. Newman, chief operating officer, National Automobile Dealers Association Public and Regulatory Affairs. "Their customers' safety is a top priority; we are pleased that GM responded quickly and responsibly to protect its vehicle owners." Chevrolet, GMC and Oldsmobile dealers will play a critical role in the recall campaign, according to Newman. "This event underscores the key role the nation's new-car dealers play in serving the public," he said. "Without them, GM would have a difficult time completing this recall quickly and safely." GM said that while such a severe recall is rare, it is not unprecedented -- although it could not immediately cite a similar case. GM said there have been no reported accidents or injuries as a result of the problem. The problem involves a lower control arm that connects each front wheel to the vehicle's suspension system. GM said defective parts -- not made to specifications by a company's supplier -- may break at the point where the control arm connects with the steering knuckle, the joint that allows the front wheels to pivot. "There is a risk of a significant loss of control," said GM spokesman Mike Morrisey. "The safest course of action is to literally get out of the vehicle." He said dealers were being instructed to bring a loaner car with them when they go to an owner's home to tow the SUV. The recalled GM vehicles, the automaker's latest generation of midsize SUVs, have been touted by the automaker for their safety. The new trucks are lower to the ground, with a longer wheelbase and an engine that sits lower in the vehicle -- all changes designed to lower the vehicle's center of gravity, improve handling and thus minimize the chances of a rollover. But of course, that assumes the front wheels will turn properly when the driver turns the steering wheel. Clarence Ditlow, director for the Center for Auto Safety, called the problem with the SUVs "a very serious safety defect" and said, "It's the worst possible launch for a new vehicle." Ditlow said the center and GM are in complete agreement that the problem is potentially so serious that owners should park their vehicles. The automaker said it has produced 30,000 of the vehicles but only 6,000 have been delivered to customers -- 4,800 in the United States and the other 1,200 in Canada and Mexico. Chevrolet, GMC and Oldsmobile dealers were notified of the problem on the afternoon of April 5 and told not to sell the vehicles, or even allow customers to test drive them. The SUVs have only been on the market about three weeks, since mid-March. The defect was discovered by dealers as they were conducting pre-delivery inspections. In one case, Morrisey said, the part broke after a dealership employee started driving it away from the truck that delivered it. Morrisey said he was unable to identify the dealerships where the defect was discovered or where they were located. GM would not identify the supplier. Officials at the National Highway Traffic Safety Administration said GM immediately notified the agency of its actions, as it was required to do by federal law. "This is something they discovered and they did something about it as they are supposed to do," the agency spokesman said. In addition to recalling the new SUVs already on the road, GM said it was shutting down the plant in Moraine, Ohio, where the vehicles were made, until April 16 to fix the problem. GM said the temporary halt in production at the Ohio plant will affect more than 4,000 workers. GM's midsize SUVs face a number of new competitors, including Ford Motor Co.'s redesigned Ford Explorer and Mercury Mountaineer and Toyota Motor Corp.'s Toyota Highlander.