The electricity is back on in Saskatchewan after a massive power outage hit the province early Tuesday.

The power went out around 4:15 a.m. CT, briefly affecting about 60 per cent of the province — hundreds of thousands of people.

Some people had their lights back in less than 15 minutes, but others had to wait several hours. Saskatoon, the largest city in the province, experienced few problems.

By 11 a.m. CT, power had been restored to virtually everywhere in the province, SaskPower officials said.

According to SaskPower spokesman Larry Christie, there was a major "system disturbance" in the western U.S. power grid early in the morning, and it affected the power grids in Saskatchewan, Manitoba and Alberta.

The Queen Elizabeth II power station in Saskatoon tripped off, as did four generating units at the Boundary Dam power plant near Estevan, Sask.

The province disconnected its links to neighbouring provinces until it could bring its own generators back online.

Power was returned on a "rotational basis" to ease the strain on the provincial grid, Christie said. The last similar outage was in the 1980s, when it took about six hours to bring most customers back on line.

Mother Nature blamed

In neighbouring Manitoba, the power grid was only slightly affected, according to officials at Manitoba Hydro. Manitoba's grid connections to Saskatchewan and Ontario immediately turned off, so that problems in one province wouldn't affect others.

Manitoba's mostly hydro-based system has greater flexibility and so fared better under the circumstances, Manitoba Hydro spokesman Glen Schneider said.

"It's not sensitive to over-frequency situations as some of the thermal plants, which Saskatchewan relies upon," he said. "It's just the nature of the technology."

SaskPower later said the problem was connected to some downed transmission lines in Minnesota and the fact that Saskatchewan imports power.

The manager of SaskPower's grid control centre, Dennis Felgate, said crews will be collecting data to find out exactly what happened.

"Disturbances happen," he said. "There's no guarantee that power systems [are] going to stay stable 100 per cent of the time. Mother Nature has something to say about that."