Updated

Two federal regulators were in the control room of a Midwest power grid manager as the nation's biggest blackout spread, giving U.S. officials an eyewitness account that could prove crucial to an investigation, authorities revealed Thursday.

Even before the cascading blackout, the Federal Energy Regulatory Commission (search) had been keeping a close eye on the Midwest Independent Transmission System Operator (search), now a focus of the broad inquiry into the failure to isolate the Aug. 14 crash.

Power lines owned by Akron, Ohio-based FirstEnergy Corp. (search), which is at the center of the probe, were among several lines in the Midwest that failed last week in the hours before the outage multiplied, the chief executive of the organization known as the Midwest ISO said Thursday.

James P. Torgerson declined to say where and when those problems occurred, whether the number of failures was unusual, or whether they were believed linked to FirstEnergy's subsequent line failures and the larger outage that spread minutes later.

"We don't want to muddy the water by speculating about what happened and why," Torgerson said during a news conference.

The outage darkened homes and businesses in eight states and in Ontario, Canada. A U.S.-Canada task force took over the investigation this week, seeking to determine the cause and to figure out ways to prevent another blackout. The Department of Energy (search) plans to send two investigators to Midwest ISO offices early next week.

FirstEnergy was beset by at least three collapses that may have triggered the blackout. Unexplained voltage swings knocked out a generator in its Eastlake power plant. Later, a high-voltage power line tripped off. Soon after, another power line, heated by the extra voltage it absorbed from previous failures, drooped into a tree and shorted.

On Thursday, a Philadelphia law firm sued FirstEnergy on behalf of investors, accusing the utility of misrepresenting earnings.

Torgerson confirmed that the grid manager initiated three calls to FirstEnergy, a member of the Midwest ISO, within an hour before the outages spread. The Midwest ISO also contacted counterparts that oversee neighboring segments of the power grid, including PJM Interconnection, which monitors all or parts of seven mid-Atlantic states, he said.

Torgerson refused to offer details of the contacts. He also wouldn't answer questions about Midwest ISO's initial findings about its response during the outage.

Beginning May 1, the Washington-based Federal Energy Regulatory Commission sent two staff members on a yearlong assignment to the Midwest ISO's suburban Indianapolis offices in Carmel to help it get through its formative stages, federal and Midwest ISO officials said. The Midwest ISO began operations in February 2002.

After lines went down in the Cleveland area and the blackout grew, the two federal regulators were granted 24-hour access to the Midwest ISO's control room, Dan Larcamp, a FERC staff director, said in a news conference at the regional organization's offices.

"It allowed our commission to have a very timely understanding of what was happening on the grid, and that type of information exchange from our perspective at the Federal Energy Regulatory Commission was very beneficial," he said.

The two staff members listened as Midwest ISO discussed the blackout in telephone calls with representatives of the nation's grid watchdog, the North American Electric Reliability Council (search), Larcamp said. Officials declined to discuss the content of the calls.

A FERC spokesman, Bryan Lee, said that the Midwest ISO "is a new market institution that we're encouraging the development of, so it's helpful to have staff on site."

The Mideast ISO began operations last year overseeing power transmissions on lines controlled by 23 utilities with little history of close cooperation. Its members are spread in a hopscotch pattern from Ohio to Montana and the Canadian province of Manitoba.

The Midwest ISO is seeking greater powers to meet emergency needs by overseeing moment-to-moment electricity transfers on the spot market and gain the capability to interrupt transmissions and potentially isolate outages before they spread — powers some other regional grid managers already possess.

An application to run its own spot electricity market beginning in March is pending before FERC. Torgerson said the Midwest ISO was reviewing whether to modify the application in light of last week's outage.

Torgerson declined to comment on whether changes to his organization's authority could leave it better-positioned to limit future outages.

"I think we're going to have to let the investigation run its course, and see what recommendations come out from that," he said.