UPDATE: Wellesley police reported that the park has been re-opened and the situation resolved as of Thursday afternoon.
Wellesley police are joining forces with Dover and Wellesley fire department personnel to address a hazardous materials problem at Elm Bank Reservation on the Wellesley/South Natick/Dover line at Rte. 16 (technically, the incident is in Dover, though the Elm Bank entrance is in Wellesley).
According to the police, Elm Bank is closed until further notice to vehicle traffic due to a chlorine leak at a pumping station on the property. The leak is believed to be contained inside of a building, but a regional HazMat team is on the scene to address the problem.