The Indian Point nuclear power plant will be testing its emergency siren system across the Hudson Valley this evening.

All 172 sirens are expected to sound at full volume for about 4 minutes after 6 p.m. and should be heard in Westchester, Rockland, Putnam and Orange counties.

Plant officials stress that the sirens are not a signal to evacuate. In an actual emergency, the sirens would sound to alert the public to tune in to a local EAS radio or television station for important information and direction.

The plant is scheduled to be taken completely offline by 2021 after an agreement between Gov. Andrew Cuomo's office and Entergy, the company that owns Indian Point.