A fire broke out shortly before 9 p.m. Thursday at The Union Oyster House in downtown Boston.
Restaurant goers were evacuated, as were at least three neighboring restaurants. For those eating inside, it was an unexpected ending to their meals.
"We were sitting there eating some oysters and turned around - somebody opened the door and a big rush of smoke came into the building," Sean Earnest said.
"The waitress came up and said 'There's currently a bunch of smoke - please evacuate the building,'" added Hynes Batten.
First responders reported smoke damage inside the historic restaurant.
A fire department spokesman said the fire apparently started on the outside of the building, near light fixtures, before the smoke poured inside. He said firefighters took extra care because of the history of the building and avoided breaking out windows.
A post on the restaurant's Facebook page Friday afternoon thanked firefighters and said it will remain closed through the weekend but could reopen Monday, after inspections are performed.
No one was injured in the blaze.
The Union Oyster House is the oldest restaurant in Boston and the oldest restaurant still serving in the United States.
It opened its doors to the public in 1826. It is recognized as a national historic landmark and was a popular dining spot for the late President John F. Kennedy.