Saturday was not a good day for anyone flying in or out of Minneapolis-St. Paul International Airport.

"It's just been a madhouse," said Lorraine Potts, a volunteer travel assistant.

Travelers were caught in a 20th-century time warp when they had to use rolling staircases and buses instead of electricity-dependent jetways because of a power failure in part of the main terminal. The outage continued until about 6:30 p.m., when power was restored at three of the four concourses affected, Melissa Scovronski, spokeswoman for the Metropolitan Airports Commission.

Delta Airlines handed out about 1,000 hotel vouchers to passengers who couldn't be rebooked until Sunday, Scovronski said.

She said electricians isolated the problem in the B concourse, where 16 gates remained without power Saturday night. The cause was still unknown.

All of the shutdowns affected flights operated by Delta Airlines or its regional carriers, meaning "if you're not trying to fly Delta, you're probably still golden," Scovronski said.

She said many regional flights of Delta partners were likely to be canceled Sunday. Passengers should call or contact Delta or its affiliates before going to the airport.

Xcel Energy spokeswoman Mary Sandok said the utility's crews were assisting airport workers trying to get the power back on, but that the outage occurred on the airport's grid, not the electric company's.

Hundreds lined up to rebook flights, including Kevin and Mary Sarvis, who were trying to get home to Pierre, S.D., after visit to Disney World in Florida.

"I thought we left the lines at Walt Disney World," Mary Sarvis said. "Now we have to spend the night in a stupid hotel."

A Delta Airlines employee who asked not to be identified said the lines of stranded passengers trying to rebook flights at one still open concourse were "the longest I've ever seen."

The power failure began about 8:30 a.m. and eventually led to the shutdown of about 80 gates on four concourses, leaving many passengers stranded, said Scovronski.

Concourses A, B, C and D in the main terminal, which used to be known as the Lindbergh Terminal, were closed most of the day. The three remaining concourses stayed open. Arriving Delta flights were parked in remote areas, unloaded with old-fashioned rolling stairways and then ferried passengers on MTC buses to the terminal, Scovronski said.

The airport's other terminal, formerly called the Humphrey Terminal, was unaffected.

By midafternoon, it was impossible to say how many flights had been affected because the airport's computer link with Delta Airlines, the airport's dominant carrier, wasn't functioning, she said.

Passengers with delayed flights were either booked in hotel rooms or given the option of spending the night on sleeping mats provided by the airport, she said.

Some were disgruntled, but others made the best of it.

"I'll miss out on seeing friends tonight" in Chicago, said Kris Kirkegaard, who had flown in from San Diego. "But maybe I can catch up with some old friends here, because we used to live here."

Bob von Sternberg • 612-673-7184