How news of the leak at Prairie Island nuclear plant unfolded Thursday:
Operators at Prairie Island nuclear plant declare an alert after workers discover sodium hypochlorite -- 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.
Xcel Energy, which owns the plant, sent out an emergency notification alert at 4:01 a.m.
The Nuclear Regulatory Commission contacts Prairie Island Indian Community Tribal Council President Johnny Johnson and the Prairie Island Indian Community immediately initiates its Emergency Response Plan.
Ellsworth Community School District sends out a notice saying school buses will be delayed, but it is not known how long.
Xcel Energy, owner/operator of the plant, sends out a press 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.
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.
The Minnesota Department of Public Safety announces it has activated its Emergency Operations Center and is monitoring the nuclear plant situation.
An update from the Ellsworth School District alerts parents that school will begin two hours late.
The Prairie Island Indian Community uses its phone alert notification system to advise employees and community members of the chlorine leak at the plant.
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.
Goodhue County Emergency Operations Center repeats the alert sent out earlier by Xcel Energy.
The federal Nuclear Regulatory Commission announces that its resident inspectors are monitoring plant 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.
Minnesota officials and Xcel Energy hold a press conference.
A Prairie Island nuclear plant crew is working to clean up the chemical spill of more than 500 gallons of sodium hypochlorite that occurred seven hours earlier.
Operators at the nuclear plant officially terminate the alert that was declared at 3:53 a.m. in response to the chemical spill.