Operations are back to normal at Minneapolis-St. Paul International Airport after an early morning power failure on Monday led to flight delays and long lines at security checkpoints.

The outage on the south end of the terminal affected the Delta Air Lines ticketing and check-in areas on the main level and portions of the F and G concourses. The outage also led to the closure of the south security checkpoints for about three hours, said airport spokesman Patrick Hogan.

Power went out about 3:30 a.m. and returned by 6 a.m., Hogan said. That led to long lines at the north security checkpoint, which did remain open, Hogan said.

"It's possible people on some of the earliest flights could have missed them," Hogan said. "We had a little catching up to do."

Delta was able to check passengers in on the tram level, which is below the concourse level. However, that area does not have as much capacity, Hogan said.

Some flights were held or delayed to accommodate passengers who were running late, Hogan said.

It was not immediately known what led to the power failure. The airport had a planned outage overnight in a part of the terminal. The later outage occurred when the power failed to turn back on and a ripple effect spread the problem to other portions of the terminal, Hogan said.

By 8:45 a.m., operations had returned to normal.

"Things are good now," Hogan said.

Tim Harlow • 612-673-7768