A fire broke out at Al’s Steak House in Alexandria and damaged the shop’s one-story building on reopening day. (Clarence Williams/The Washington Post)

It turned out that joy was short-lived at Al’s Steak House.

Just hours after reopening following the death of its longtime owner, the decades-old Alexandria eatery suffered a catastrophic fire Wednesday afternoon that closed it indefinitely.

There were no injuries in the blaze, which erupted at the shop’s one-story building in the 1500 block of Mount Vernon Avenue. Fire officials are trying to determine the cause of the fire.

Firefighters were called to the shop just before 4 p.m., after a passerby noticed smoke coming from the roof. It took firefighters 45 minutes to bring the blaze under control, said Deputy Chief Byron Andrews of the Alexandria Fire Department.

[Where the cheese steak is the real deal]

Firefighters put out the blaze inside the landmark cheese steak institution in about 45 minutes, a department spokesman said. (Clarence Williams/The Washington Post)

The family who purchased the cheese-steak institution said they were inside the eatery when a customer noticed smoke coming from a light fixture. They turned it off, but the smoke continued.

“We were just getting into a groove — this was all so sudden,” said 21-year-old Emily Breeding, 21, a rising fourth-year University of Virginia student, who owns the eatery with her family.

For years, the Breedings had been customers of Al’s Steak House, which is nestled in the Del Ray neighborhood. The shop closed in December 2015, after the death last August of John Severson, who took over the shop from its namesake in 1965. After Severson’s death, the Breedings bought their favorite business.

Wednesday had been a soft reopening, and the Breedings had planned for a few first-day takeouts as they juggled to maintain continuity and the same recipes that loyal customers expected. But having the restaurant fill with smoke and forcing customers to evacuate was not what they expected.

On Wednesday afternoon, the family stood in disbelief across the street, holding back tears while they waited to hear what caused the fire and how much damage it did to the building.

“We wanted to stay true to the steak-and-cheese [sandwich] the community has been used to,” said Breeding’s mother, Dorothy, 47. “This is the last thing we expected on opening day.”

The eatery closed after the blaze, and it’s unclear when it will reopen.

Despite the shop’s twin calamities — Severson’s death and the fire — customers held out hope that their go-to source of cheese steaks would soon reopen.

“This is an institution in Alexandria; there aren’t too many places like Al’s that have been around for 64 years,” said 58-year-old Patrick Malone of Alexandria, who first ate at the shop as a teenager in 1974.

Malone said he was one of the first in line when Al’s reopened Wednesday morning. He added that he hopes the Breeding family will open the shop again.

“Thankfully no one was hurt,” he said. “Damage can be fixed. I’m an optimist.”