A Hanover-based trucking company with a long history of safety violations — including a fatal crash in August — has been ordered off the road after federal regulators found it to be an "imminent hazard" to the public.

The Federal Motor Carrier Safety Administration, which oversees interstate trucks and buses, said Wednesday that Gunthers Transport LLC must cease operations immediately. The regulator alleges Gunthers failed to follow traffic safety rules, ensure its drivers were qualified and keep its trucks well-maintained.

"Your motor carrier operation substantially increases the likelihood of serious injury or death if not discontinued immediately," the agency's notice to the company says.

The rare move comes after more than a decade of Gunthers companies and their managers running afoul of federal safety laws and regulations. The company, which has offices near Baltimore-Washington International Thurgood Marshall Airport, has registered more than 100 drivers and 18 trucks.

During a recent on-site investigation at those offices, the regulator found evidence that Gunthers drivers were on the road longer than 11 hours — the federal limit. And in the fatal crash in August, Maryland State Police found the Gunthers truck had worn tires, defective brakes and a turn signal that wasn't working.

In 1995, in the first criminal case of its type, Gunthers Leasing Transport and its president, Mark David Gunther, were found guilty of falsifying records to evade federal laws limiting the amount of time drivers can spend behind the wheel. In that case, Mark Gunther was also convicted of perjury and conspiracy to defraud. Gunther was sentenced to 30 months in prison and the company was fined $170,000.

Court records show that Gunther, 56, is a principal of Gunthers Transport, which incorporated in 2005 — several years after the earlier company declared bankruptcy. Gunther could not be reached for comment Wednesday at his home or business. Efforts by phone and e-mail to reach the company's attorney also were unsuccessful.

Wednesday's action stems from a two-year assessment of Gunthers Transport's safety performance that ended Oct. 28. The motor carrier administration found that Gunthers was "seriously deficient" in four of seven safety categories: safe driving, prevention of driver fatigue, driver fitness and vehicle maintenance.

A spokeswoman for the agency said an imminent-hazard order is "one of the strongest measures" it can take unilaterally to shut down an unsafe company. During the last federal budget year, the agency issued only 10 such orders nationwide, she said.

"These types of actions are exceedingly rare," said an American Trucking Association spokesman, Sean McNally.

Over the last two years, Gunthers' 18 vehicles were inspected 190 times and were deemed unfit for service during 58 percent of those inspections — about three times the national average — according to the motor carrier administration, a division of the U.S. Department of Transportation.

Gunthers' drivers were inspected 242 times in the past 24 months. Almost 16 percent of the time, those drivers were not fit to be driving, records show. The national average for drivers being taken out of service is 5.5 percent.

The agency said it found evidence that Gunthers allowed drivers to begin trips without required safety inspections, to operate trucks beyond the federal limit of 11 hours a day, and to operate vehicles that were in dangerous condition. It also found evidence Gunthers either allowed or required drivers to falsify records, the agency said.

According to the agency, Gunthers has had seven serious crashes, involving four injuries and a fatality, in the past 12 months. Regulators said post-crash inspections were conducted in two of those cases — including one Aug. 8 in which one person was killed.

In that case, according to the agency, a Maryland State Police inspection found multiple mechanical defects in the truck, including nine serious enough to have put the vehicle out of service. A state police spokesman, Greg Shipley, said details about the crash were not immediately available.

After a crash April 28, in which a Gunthers driver left the roadway and hit a fixed object, an inspection found that the operator did not have a required medical certificate and was driving a tractor-trailer that had not been inspected.

The agency said serious safety problems have been found in "substantially all" of Gunthers Transport's vehicles on which inspections were performed within the past 61/2 months. According to the motor carrier administration, the company had been the subject of two compliance reviews in 2008 and two this year, in January and April. Among the findings were that Gunthers has been operating vehicles that had been listed as out of service and keeping false records of drug and alcohol violations.

The company received about 60 citations over the last two years regarding drivers being on the road for a longer period of time than allowed by law.

In addition to the company's federal problems, Mark Gunther has also had at least one run-in with Maryland officials over the condition of his trucks. Court records show he was found guilty in April of a violation of state law on maintenance of commercial vehicles and was fined $530.