The Russell Field entrance to the Alewife T station, seen Monday, is closed for repairs. (Photo: Marc Levy)

The closing of the Russell Field side of the Alewife red line T stop wasn’t due to vandalism, but to a dramatic example of wear and tear at the aging station, the MBTA said Wednesday.

The plywood replacing windows and fencing blocking access to the Russell Field entrance – and, on the inside platform, blocking access to stairs, escalators and elevators there – resulted from the glass in large windows falling early Sunday, said Joe Pesaturo, director of communications at the Massachusetts Bay Transportation Authority.

“Some street-level glass panels near the Russell Field entrance/egress became dislodged and landed on the brick path just outside the station,” Pesaturo said. “The station was closed at the time and no one was in the area.”

The damaged section has been replaced temporarily by plywood while staff work to determine what caused the panels to dislodge, Pesaturo said.

MBTA Transit Police confirmed there was no vandalism at play where the glass fell. The state has cameras around the area that would have spotted human involvement.

The T system as a whole, with rail extending across Greater Boston, struggles with aging infrastructure. At Alewife, which opened in 1985, a previous sign of aging came in literally concrete form in August 2018: The 2,500-parking-space garage saw 500 spaces cordoned off after a chunk of ceiling concrete fell through the window of a car. No one was hurt.