French investigators are trying to identify a chemical applied to an electronic keypad at a Paris-area synagogue that burned more than a dozen congregants.

The Creteil prosecutor's office said Friday that analysis is still taking place on the substance, which caused light burns and eye irritation for the congregants at the synagogue in Bonneuil-sur-Marne late Monday. No one was hospitalized.

Jewish locations in France have been on high alert since the January attacks in Paris on a kosher supermarket and the Charlie Hebdo satirical newspaper.