The situation unfolded around 11:20 a.m. Tuesday, April 20 at the supermarket located on Long Island, on Cherry Valley Avenue in West Hempstead.
There have been reports of multiple shots fired, but no word on any possible fatalities or injuries.
"Nassau County Police said officers are "canvassing the area and nearby schools have been notified to lock down & secure their buildings.
"The subject has not been apprehended yet and we ask that area residents remain indoors."
This is a developing story. Check back to Daily Voice for updates.
Click here to follow Daily Voice Pittsfield and receive free news updates.