Boston firefighters are investigating a fire at the city's historic Union Oyster House.

Originally established in 1826, the building is America's oldest restaurant and is considered to be a national landmark.

Firefighters responded to the Oyster House, located at 41 Union St., just after 8:30 p.m. Thursday.

A MassLive reporter at the scene said that authorities had evacuated a neighboring restaurant, the Green Dragon Tavern -- another historic structure originally built in 1657.

Both establishments are located along Boston's "Freedom Trail," a popular tourist path that features the city's most historic locations.

"We saw a blaze on a front right wooden panel of restaurant, which they eventually tore off," said Masslive reporter Kristin LaFratta, who witnessed the fire.

Officials haven't released any information regarding the fire yet.

Firefighters put out blaze at Union Oyster House. Iconic restaurant in Boston founded in 1826 @masslivenews pic.twitter.com/kX3TNnDsFw — Kristin LaFratta (@kristinlafratta) August 4, 2017

Firefighters dismantle wooden paneling in front of Union Oyster House where some smoke appeared to pouring out of. pic.twitter.com/6G9NXw8PIs — Kristin LaFratta (@kristinlafratta) August 4, 2017

This story will be updated when more information becomes available.