WASHINGTON – The federal government on Thursday shut down two bus companies that operate in Georgia for safety violations that it said pose an “immediate hazard” for travelers.

In a wide-ranging order covering three companies shuttling 1,800 passengers a day along the East Coast, the Department of Transportation found that I-95 Coach Inc. and Apex Bus Inc. did not make sure drivers were properly licensed and did not screen for drugs and alcohol, among other lapses of federal safety rules. A third company, New Century Travel Inc., was also shuttered Thursday, but it does not operate in Georgia.

I-95 Coach and Apex Bus offer routes from the Atlanta area to several East Coast cities. I-95 Coach also serves Savannah, and it has three Chamblee-based subsidiaries: Hu Mei Express Inc., Tony Bus Line Inc. and Tony Bus Express Line Inc.

Greyhound is offering a $1 fare special to anyone who bought a ticket from these companies that cannot be redeemed.

A woman answering the phone at Hu Mei Express said the bus was canceled and hung up. Calls to the New York, Philadelphia and Washington headquarters of the three parent companies were unanswered.

The low-cost buses primarily operate in the high-traffic Washington to New York corridor out of the Chinatown neighborhoods.

The DOT has issued shutdown orders to several of the subsidiaries in the past, but Thursday’s order said the companies would often elude safety changes by forming again as a new company. The agency also barred 10 people from serving bus passengers, including selling tickets.

Among the other violations, the agency found that the companies failed to regularly inspect and repair vehicles and didn't have a proper system to ensure that drivers were screened for alcohol and drug problems. Regulators also claim the companies failed to make sure drivers heeded regulations restricting their hours behind the wheel.

The DOT called Thursday’s action “the largest single safety crackdown in the agency’s history.”

“These aggressive enforcement actions against unsafe bus companies send a clear signal: If you put passengers’ safety at risk, we will shut you down,” U.S. Transportation Secretary Ray LaHood said in a statement. “Safety is and will always be our highest priority.”

The bus companies that carry passengers along I-95 came under scrutiny after several deadly bus crashes last year. In one incident, a bus returning to New York from Connecticut on a routine casino run in March 2011 slammed into a barrier, killing 15 people. In May 2011, a bus traveling from North Carolina to New York veered off the highway in Virginia, killing four people and injuring another 50.

Federal transportation officials shut down several bus companies last summer after reviewing their operations, and regulators have tried to crack down on so-called "ghost companies" that pop up quickly and can re-open under different names if they are shut down.

These rogue operators are a growing problem in the passenger bus industry, which includes an estimated 4,000 companies that carry hundreds of millions of passengers each year. The crackdown was cheered by transportation safety advocates who have long complained about fly-by-night operators who have been difficult to regulate.

Jerry Kremer, counsel to the Bus Association of New York state, a group that never has included the banned operators, said barring both the companies and the specific individuals from the bus business was a major step. He said the "ghost companies" often manage to stay under the radar by advertising in foreign language media and take advantage of states with less rigorous industry regulations to get licensed. They manage to stay popular thanks to their low-cost model, Kremer said.

Kremer said consumers "try to find the cheapest form, and the cheapest form is not always the safest form."