Montgomery County officials have closed off some sidewalks around a nine-story glass office building at 4500 East-West Highway in downtown Bethesda because of glass breaking and falling. (Amanda Farber)

Montgomery County officials closed sidewalks around a nine-story glass office building in downtown Bethesda on Tuesday, a day after a piece of glass fell off the building and crashed onto the sidewalk.

County officials say it’s the third time they’re aware of since April 2017 that glass has fallen from the five-year-old building at 4500 East-West Highway. No one has been injured. The sidewalks are frequently used by office workers and students from Bethesda-Chevy Chase High School and Our Lady of Lourdes Catholic School across the street.

Amanda Farber, a nearby resident who has been tracking the problem, said bits of shattered glass on the sidewalk near a building entrance on Pearl Street on Monday appeared to have come from an eighth-floor window. By her count, Farber said, it was at least the sixth window to have fallen, cracked or bulged.

Diane Schwartz Jones , Montgomery’s director of permitting services, said she couldn’t speculate on what’s causing the glass to fall. After the second incident suggested a problem with the building, she said, the county required the owner, D.C.-based Carr Properties, to have an independent structural engineering review.

After the third incident Monday, Jones said, the county sent an inspector to the building and closed two surrounding sidewalks. It also ordered Carr to build protective canopies, strong enough to withstand falling objects, on the three sides of the building with pedestrian access by Feb. 25. She said county officials plan to meet with Carr as soon as Wednesday to discuss a longer-term plan.

A worker cleans up glass that shattered on the sidewalk of Pearl Street in downtown Bethesda on Monday. (Amanda Farber)

Before Monday, the last incident had occurred in August 2017, she said. Because county officials haven’t seen any glass fall, she said, it’s unclear if it has rained down in pellets from being tempered glass or if large chunks fell and shattered on impact. Pieces of glass left behind in the window Monday, she said, “indicate severe fracturing or shattering.”

“Clearly something needs to be done here,” Jones said. “Why are these windows falling out, and how is the area being secured to make sure no passersby are injured? It’s the safety of the people who are walking or bicycling below — that’s what we’re really concerned about.”

In an emailed statement Tuesday, Carr spokeswoman Emily York said some of the glass has had “imperfections.” She said the company plans to install street-level canopies by this spring as “an additional precaution,” even though its glass consultants have said the “risk of any ongoing glass breaks declines significantly with time.” The building opened in 2014.

“The building was constructed with 100% tempered safety glass that breaks into small granular pieces,” York said. “Unfortunately, imperfections in the glass can cause breaks, which has happened infrequently (approximately 1% of total panes) since the building was delivered in 2014.”

York didn’t respond to follow-up questions seeking more details about the “imperfections” and how the company will protect passersby until the canopies are installed.

Bethesda-based Clark Construction built the “all-glass curtainwall building” for $39 million, according to Clark’s website. A Clark spokeswoman referred questions to Carr.

The building’s architect, D.C.-based Shalom Baranes Associates, also referred questions to Carr.

Naya Robitaille, who lives nearby, said she vividly remembers the explosive sound of glass breaking on the Montgomery Avenue sidewalk that she and a friend had just left to cross the street while walking to lunch in April 2017. It appeared to come from part of a seventh-floor window and seemed to be from a larger chunk or chunks that shattered on impact, she said.

“We just stood there in shock,” Robitaille said. “We were just looking at each other thinking, ‘Oh my god, what just happened? We could have been under that.’ ”

Robitaille said she was surprised to hear that, almost two years later, it had happened again.

“It’s shocking that the building is still inhabited and allowed to sit there with its glass falling everywhere,” she said. “I’m shocked it hasn’t been fixed and no one has been hurt. It seems crazy to me.”

Lydia Chang said she remembers seeing orange cones and yellow tape blocking off an area near the building in February or March 2017, when her family’s restaurant, Q By Peter Chang, was being built out on the ground floor. A building engineer told her birds had flown into a window, she said.

Then in fall 2017, after glass had fallen from the building that August, Carr put up scaffolding as a protective covering over the restaurant’s front entrance, she said. It’s still there.

“They said it was a design issue, and they had no idea why it kept happening,” Chang said. “They said they’d do everything they could to make sure no one got hurt.”

The restaurant no longer seats diners on its outdoor patio.

She said she would like a permanent solution that would prevent the glass from falling rather than simply protect people below. She’s concerned, she said, about her employees and customers as they enter and leave the building.

Farber said she has photographed at least six glass-related incidents since April 2017, including the one Monday.

“They need to deal with this,” she said. “It’s been going on too long.”