Washington (CNN) -- Calling it the single largest crackdown on bus companies that the Department of Transportation has ever undertaken, Secretary Ray LaHood announced Thursday the agency has shut down 26 bus operators for breaking federal safety rules.
He declared the operations imminent hazards to public safety.
Officials also ordered "10 individual bus company owners, managers and employees to cease all passenger transportation operations, which includes selling bus tickets to passengers," the Transportation Department said in a news release.
"These operators transport over 1,800 passengers a day, up and down the I-95 corridor from New York to Florida," LaHood said. "This crackdown is a victory for bus safety and the people who ride these buses."
The 26 shutdown orders apply to nine active companies, 13 companies already ordered out of service that were continuing to operate, three companies attempting to apply for operating authority and one ticket seller, the Transportation Department said.
All told, the companies operate between 30 and 35 buses and are based out of Georgia, Indiana, Maryland, New York, North Carolina and Pennsylvania, according to the department.
Officials allege the companies operated buses that needed repair, failed to test drivers for alcohol and drugs, failed to properly document driver medical qualifications, and kept the drivers behind the wheel beyond legal limits.
"People get up every day and use a lot of different forms of transportation without thinking about the safety factor, and we don't want them to worry about the safety of the bus they ride on or the highway they drive on," LaHood said.
The crackdown was triggered after a series of deadly bus accidents and was the culmination of a yearlong investigation by the Federal Motor Carrier Safety Administration, the Transportation Department arm tasked with regulating bus safety.
On May 31, 2011, one year to the day before Thursday's announcement, four passengers were killed and 53 others injured in a Virginia bus accident. Investigators claim fatigue on the part of driver Kin Yiu Cheung caused the bus to run off the road and overturn. Cheung faces four counts of involuntary manslaughter and is slated to go to trial June 25, the Caroline County Virginia court clerk told CNN.
"The crash and other fatal crashes like it that occurred along I-95 last year led our agency to conduct this unprecedented one-year investigation into dangerous and illegal bus companies operating in violation to our basic safety standards," Federal Motor Carrier Safety Administrator Anne Ferro told reporters.
In another accident, Ophadell Williams, 40, was behind the wheel of a tour bus that crashed into a roadside barrier in New York, killing 15 passengers. After the crash, New York state's inspector general revealed that Williams should not have been given a commercial bus driver license, but was able to obtain one by allegedly using fake names and false information.
The Transportation Department's statement said it has doubled the number of bus inspections of the nation's estimated 4,000 passenger bus companies, from 12,991 in 2005 to 28,982 in 2011.
The Federal Motor Carrier Safety Administration shut down three primary companies -- Apex Bus Inc., I-95 Coach Inc. and New Century Travel Inc. -- which oversaw a broad network of other bus companies.
"Through the course of our investigations our enforcement teams found multiple patterns of glaring violations by the three networks of enterprises," Ferro said. She said the companies "found loopholes" and managed to get back on the road even after authorities had shut them down.
The crackdown on alleged rogue companies was applauded by the American Bus Association, a trade group representing motor coach and tour bus companies.
The agency's actions "went far beyond random roadside inspections, and ABA very much supports these types of law enforcement efforts. We will continue to support (the agency), and we urge our members to operate at the highest level of safety," association President Peter Pantuso said in a statement to CNN.
Buses remain a popular mode of transportation for Americans, carrying almost as many passengers each year as commercial airlines. About 750 million passengers ride passenger and tour buses each year, compared with round 800 million passengers on airlines, according to American Bus Association spokesman Dan Ronan.
In March, the Transportation Department announced a new program, "Look Before You Book," and a smartphone app that allows users to access the safety records of nearly 6,000 interstate commercial passenger carriers. The records consist of safety and inspection data about private bus lines, school buses and tour bus operators.
To use the app, passengers can search the bus company or the company's registration number. Information provided by the app reveals who owns the bus and the bus company's safety record.
A check of the app by CNN showed the companies involved with Thursday's announcement were "not allowed to operate."