The alert declared by operators at the Prairie Island Nuclear Generating Plant as a result of a chemical spill this morning was terminated at 2:08 p.m. today.

Operators declared the alert at 3:53 a.m. today after workers discovered sodium hypochloride, commonly known as chlorine bleach, leaking from a tank in the screen house. The chemical is used to treat water that is brought into the plant for cooling.

The incident released no radioactive material, and officials said there is no danger to the public. No workers have been injured at the plant.

The sodium hypochloride leaked from a tank and is fully contained within a berm. The cause of the leak is being investigated.

As a precautionary measure, Prescott and Ellsworth school districts delayed the start of classes two hours.

"We weren't sure what the release was and so we canceled school until we found out," Prescott Superintendent Roger Hulne said, adding that he decided a two-hour delay was sufficient when he discovered the leak was completely contained.

A flurry of Facebook and Twitter posts as well as text messages flying back and forth indicated those districts were closed, students said.

In fact, classes were only delayed. Ellsworth School District sent out an automated message to households just before 8 a.m. stating it was safe to hold classes.

The River Falls School District also sent out a recorded notification to parents advising of the situation. Superintendent Tom Westerhaus noted that the Pierce County Emergency Management Center had been activated.

Delaying schools is standard practice, authorities from Goodhue and Pierce counties told the R-E, for those communities in the path of any potential leak. The Wisconsin school districts are east/northeast of the plant, which is on the Mississippi River, and the wind is blowing in that direction.

An alert is the second lowest of four emergency classifications established by the federal Nuclear Regulatory Commission. The purpose of an alert is to assure that emergency personnel are readily available to respond and to provide off-site authorities with current status information.

The Minnesota State Emergency Operations Center and Joint Information Center were activated today, as well as the Goodhue County Emergency Operations Center.

To keep telephone lines open for emergency communications, Xcel Energy asks the public not to call the plant site or Xcel Energy. The state of Minnesota is establishing a toll-free emergency number to respond to inquiries about the incident. The number will be publicized as soon as it is operational.

The Prairie Island nuclear plant is 28 miles southeast of Minneapolis-St. Paul and about six miles northwest of Red Wing. The plant's two pressurized water reactors generate 1,076 megawatts of electricity, enough to power nearly 1 million homes. Both units continue to operate at full power.

How news of the leak at Prairie Island nuclear plant unfolded

3:53 a.m.

Operators at Prairie Island nuclear plant declare an alert after workers discover sodium hypochloride -- commonly known as chlorine bleach -- leaking from a tank in the screen house.

The chemical is used to treat water that is brought into the plant for cooling.

6:30 a.m.

Ellsworth Community School District sends out a notice saying school buses will be delayed, but it is not known how long.

7:06 a.m.

Xcel Energy, owner/operator of the plant, sends out a release regarding the chlorine leak. According to Xcel, no release of radioactive material is associated with the event and there is no danger to the public.

7:14 a.m.

The Pierce County Emergency Operations Center warns the public about the incident at the nuclear plant, and suggests tuning into radio stations KCUE, KWNG and WCCO for more information.

7:27 a.m.

The Minnesota Department of Public Safety sends out a release saying it has activated its Emergency Operations Center and is monitoring the nuclear plant situation.

7:52 a.m.

An update from the Ellsworth School District alerts parents that school will begin two hours late.

7:55 a.m.

The Minnesota Department of Safety announces it will hold a news conference at 9 a.m. in its media briefing room to address the status of the nuclear plant.

8:04 a.m.

Goodhue County Emergency Operations Center repeats the alert sent out earlier by Xcel Energy.

8:41 a.m.

The federal Nuclear Regulatory Commission announces that its resident inspectors have responded to the plant and are monitoring workers' handling of the incident.

The leak has been isolated in a berm around the screen house and a chemical crew is on the way to clean up the leak, the NRC says.

9 a.m.

Minnesota officials and Xcel Energy hold a press conference.

2:08 p.m.

Operators at the nuclear plant terminate the alert declaration.