New York (CNN) -- Rail service on Amtrak's Northeast Corridor was suspended for more than an hour Tuesday morning because of a power problem, officials said.
The cause of the problem, which apparently occurred between Perryville, Maryland, and Washington, was unknown, said Amtrak spokeswoman Karina Romero. Power was restored to all lines at 9:01 a.m., she said, but resumption of service would be staggered in order to minimize the load on the circuits.
Some trains totally lost power, including lights and air conditioning, and service to those would be restored first, Romero said.
As of 10:05 a.m., all trains were moving again, she said, but delays were ranging from 20 minutes from trains leaving Washington at the time to two hours for trains that were backed up along the affected lines.
"At approximately 7:45 a.m. ET this morning Amtrak experienced a service disruption following a voltage problem affecting train service between Washington and New York and Philadelphia to Harrisburg [Pennsylvania]," Amtrak said in a statement. MARC (Maryland Area Regional Commuter), SEPTA (Southeast Pennsylvania Transportation Authority) and New Jersey Transit commuter services were also affected, the company said.
Those regional trains use Amtrak's overhead power lines, Romero said.
It was the second time in two weeks that power problems have affected Northeast Corridor service.
Romero said the outage was "a power trip, like a circuit breaker." It "had a ripple effect," she said. It showed up as an overload somewhere along the line and tripped protective circuitry, she said.
Penny Bassett Hackett, spokeswoman for New Jersey Transit, told CNN just before 9 a.m. ET that Northeast Corridor and North Jersey Coast Line service was being restored with delays of 60 to 90 minutes. There were reports of low voltage, she said, and as a precaution all New Jersey Transit trains were pulled into the nearest platforms.
CNN's Soledad O'Brien said she was headed to Baltimore, Maryland, on a train when the problem struck. The trains went on battery power, but ran out, she said, and were stopped waiting for the problem to be fixed. "We're kind of in the middle of nowhere," she said.
She said Amtrak personnel were "really good" about keeping passengers updated via the public-address system, and those on the train seemed to be taking the delay well.
About 9:05 a.m, O'Brien wrote in an e-mail that the train had regained power, but had not received authorization to move yet. Four minutes later, she sent an e-mail saying, "We are moving shortly. They're doing a check of the train and we will be back and running soon, I'm told."
CNN's Paul Courson and Yuliya Talanonova contributed to this report.