A two-alarm fire early Wednesday damaged Metro’s headquarters building in downtown Washington.

Vito Maggiolo, a spokesman for the D.C. fire department, said firefighters arrived about 6 a.m. to find “fire was showing from the top floor” of the eight-story building near Sixth and F streets NW. Fire officials said the blaze was extinguished quickly.

No one was injured and cause of the fire is under investigation. A Metro spokeswoman said there was “no disruption to service.”

Metro is expected to vacate the building — the Jackson Graham Building, which is more than 40 years old — by at least December 2022 and move to a more modern building under construction at L’Enfant Plaza.

Metro is relocating as transit agency officials consider the Graham building to be outdated, lacking an adequate fire sprinkler or suppression system.

Most staff members who typically work at Metro’s headquarters have been working from home because of the coronavirus pandemic. Transit agency spokesman Dan Stessel said the fire originated on the northwest corner of the eighth floor, which contained unoccupied offices. The preliminary cause, he said, appears to be accidental, but the investigation is ongoing.

“We are grateful all employees and occupants were safely evacuated during this morning’s fire at Metro’s headquarters,” the agency said in a statement. “Thanks to the quick response from DC Firefighters, the fire was quickly contained, and there were no reported injuries to Metro employees or first responders. We are currently assessing the damage and working closely with [the fire department] to identify the cause of the fire.”

D.C. Fire Chief Gregory M. Dean said at a news conference that people who were in the building at the time were evacuated, but he did not know how many. He said it took firefighters from a station across the street about 20 minutes to extinguish the blaze.

Dean said the building is “older and did not have sprinkler systems on the upper floors.” The building also doesn’t have smoke detectors. Dean said firefighters were notified by an alarm.

The Washington Metrorail Safety Commission said on Twitter that Metro’s rail operations control center was “active in the building at the time of the evacuation.” Officials said control was switched to the Carmen Turner Facility, a complex in Hyattsville where many of Metro’s operations occur.

Because of the pandemic, Metro has been splitting its control staff between the Hyattsville center and the Jackson Graham building, which has a backup center, to help employees with social distancing. Control staff who had been working at Metro’s headquarters will shift back to the main control center, Stessel said.

Most of the downtown building, which includes the backup control center — as well as offices for Metro Transit Police Chief Ronald A. Pavlik Jr., payroll staff and General Manager Paul J. Wiedefeld — were not harmed, Stessel said. But Metro will have to remediate damage from water that poured into other floors from the fire fight. It’s not known how long that could take.

“We’re still assessing the damage,” Stessel said Wednesday afternoon.

About 1,100 employees worked out of the building before the pandemic.

The safety commission also said it “will be working with #WMATA and fire investigators to learn more about the cause, response and any damage.”

Metro’s new headquarters at L’Enfant Plaza remains under construction.

In February, the transit agency reached a deal to lease the Jackson Graham Building for 99 years to the development team of regional developer Stonebridge and the Rockefeller Group for upward of $130 million.

Developers plan to remake the building, which can house more than 1,500 employees, into an expanded retail and office space. They intend to gut the structure, add three floors and create a more transparent facade with more windows. The one-acre property will also include walkways that developers say will blend in with the neighborhood and draw people in and out of the building on their way to events at Capital One Arena, which is across the street, or elsewhere.

Located between Chinatown, one of the city’s busiest shopping and entertainment districts, and the Judiciary Square area, home to government buildings and parks, the Jackson Graham building was built in 1974 and named after Metro’s first general manager.