Griff’s Irish Pub, Houston’s premier restaurant since 1965, was badly damaged by fire.

Griff’s Irish Pub, Montrose’s iconic business that bills itself as the oldest sports bar in Houston, was extensively damaged Friday in a morning fire.

The Houston Fire Department said the fire started shortly before 4 a.m. Friday, no one was inside at the time and no casualties were reported. As of Friday morning, the cause was still being investigated and HFD spokesperson Alicia Whitehead-Brough said in an email: “The building appears to be completely destroyed, with an estimated damage of $630,000.”

“Griff’s will be closed until further notice while we rebuild,” the pub wrote in a Facebook post. “Thanks for your support!”

Griff’s, which has operated at 3416 Roseland St. since 1965, did not immediately respond to messages asking for more comment about the fire and its recovery plans.

The 2,392-square-foot pub was built in 1955 and is located on a 5,750-square-foot lot near the northwest corner of Roseland Street and Harold Street, according to the Harris Central Estimated District. As of January last year, the property’s appraised value was $422,595.

Griff’s was founded by Michael “Griff” Griffin, a Boston native who played basketball at St. Thomas University and stayed in Houston. He sold the pub in the mid-1990s and was a candidate for the Houston City Council several times.

Mark Norris/Houston Public Media

The bar has long been a popular spot to watch local sporting events such as Astros, Rockets and Texans games. It hosts the annual St. Patrick’s Day Festival and a fundraiser is scheduled for the end of this month.

The pub’s brief Facebook post about the fire had garnered more than 100 comments by late Friday morning, with new and old customers expressing shock and sadness at the news, as well as sharing their memories and what they love most about Griff’s.

“We are devastated,” one customer wrote. “Griff’s is a place where everyone belongs together, you can sit with a complete stranger, make a new friend and have a great time, and you feel right at home when you walk in the door.”