Already reeling from mechanical woes, management problems and chronic money shortages, Amtrak struggled to deal with a massive power outage Thursday that stranded tens of thousands of passengers in hot, smelly cars, some even underground.

Power was out for nearly three hours, affecting not only the nation's passenger railroad, but also commuter lines in New Jersey, Maryland and Pennsylvania. Many passengers simply got out of stuck rail cars and walked to the next station.

"I'm going to take a long, hard look at the Delta shuttle next time," said Jeff Oppenheim, a New York actor and director who was stuck for three hours, 15 minutes in a dark, sweltering tunnel outside New York Penn Station on his way to a business meeting in Washington.

The outage, whose cause was still not determined as of mid-afternoon Thursday, caused widespread disruptions from Washington to Boston.

"It doesn't appear that there was any major physical failure, but something tripped, and there was some sequence of events and a protective system shut everything down," said Amtrak acting president David Hughes.

Amtrak officials were reviewing electronic logs to identify the sequence of events to determine what happened, Hughes said, adding that the railroad would be working around the clock to pinpoint the cause.

Hughes did not know how many Amtrak trains were affected but on a typical day, Amtrak operates 97 train departures between New York and Washington and 42 departures between New York and Boston.

Thirteen NJ Transit trains were stopped dead on the tracks by the outage, along with an additional 28 SEPTA trains in Philadelphia and eight on the MARC system in Maryland.

The outage prompted cries for change within Amtrak's management.

"If there was ever proof that Amtrak is being terribly mismanaged with unqualified people at the helm, this power outage at the height of the morning rush hour is it," said Sen. Charles Schumer, D-NY. "This outage, quite literally stopped thousands in their tracks and for a rail service that so many people rely on, this is unacceptable."

Amtrak officials declined to respond to the criticism.

Amtrak has debt of more than $3.5 billion and its operating loss for 2005 topped $550 million. It has never turned a profit in its 35 years of existence. The railroad has had a host of problems in the last year.

On April 15, 2005, Amtrak had to cancel service on its Acela Express trains because of brake problems with the high-speed trains that carry passengers between Washington, New York and Boston. Full service was not restored until September.

In November of last year, the Government Accountability Office, issued a blistering report saying Amtrak needed to improve the way it monitors performance and oversees its finances. A few days later, Amtrak fired President David Gunn. In subsequent interviews, Gunn said he was fired because he did not approve of the Amtrak board's plans on a host of issues. The board has yet to hire another president.

In 2005, President Bush proposed giving Amtrak no money whatsoever, but Congress approved $1.3 billion for the railway. Amtrak's budget request for the next fiscal year is $1.59 billion, while Bush is calling for $900 million.

Passengers stuck on trains described rapidly worsening conditions as the outage dragged on.

"When you lose the power, you lose all the flushes too," added Oppenheim, who was stuck aboard the Acela train.

"It's getting pretty hot in here, and the bathroom is getting backed up," said Mike Kenny of West Windsor, N.J., who said his commute on NJ Transit was one of the worst he had experienced in 30 years.

"It's starting to smell back here," added Krista Barry of Pennsauken, who sat on the floor of an NJ Transit train, reading a book for 90 minutes as her friends one by one called her cell phone to offer condolences on having to spend her 23rd birthday stuck on a train. "I'm going to get a big Venti cappuccino when I get home."