A woman crossing the Meridian Street Bridge in East Boston was crushed to death Tuesday afternoon as she clung to one of the two plates of the lift bridge, which then closed on top of her, according to city administration officials.
“She was screaming and screaming and screaming,” said Waldina Garcia, a 47-year-old East Boston woman, who was waiting to cross the bridge. “It’s so horrible,” she said, weeping.
Thomas Foley, a Boston police detective sergeant working the scene, said police are still trying to piece together what went wrong on the bridge. He said the woman was clearly atop the bridge when it opened, but it is unclear whether she ignored warning lights and alarms or whether the guard manning the bridge failed to ensure the bridge was clear before opening it.
“That is the issue right now. The bridge was open when she fell,’’ Foley said. “Right now it looks like a tragic accident.”
The bridge operator has been placed on unpaid leave pending the results of an investigation, which is standard procedure, said Dot Joyce, spokeswoman for Mayor Thomas M. Menino of Boston.
The bridge, also known as Andrew McArdle Bridge, is a popular route for many Chelsea and East Boston residents who travel across it to shop or go to work.
It was not immediately clear if the woman was crossing from the Chelsea side or from East Boston, officials said. Garcia said she believes the woman must have been coming from the East Boston side.
Garcia, who works at a sandwich factory in Chelsea, said she crosses the bridge every day by foot to get to her home in East Boston. She said she was heading toward the pedestrian walkway when she heard a loud foghorn and saw the blinking lights that indicated that the bridge was about to open.
The bridge operator lifted the bridge to allow a boat traveling on the Chelsea River, officials said.
Garcia said she was the only pedestrian waiting to cross from her side. She stood at the gate for about five minutes, when she suddenly heard the screams.
At least two bridge workers rushed up stairs alongside the bridge. Then she said she saw the plate on the Chelsea side go down.
“I kept waiting for them to come back down with her,” Garcia said. “But they didn’t bring her back.”
As the two plates of the bridge rose, the woman grabbed hold of one of them, clinging to it as she screamed for help and dangled over the cold water below, police said.
The bridge operator heard the woman and lowered the bridge, trying to help her, police said. Instead, the woman was crushed by the plates, police said. The bridge operator, who works for the city’s Department of Public Works, was so distraught that he was rushed to a hospital for what officials would only describe as treatment for stress. His name was not released.
Emergency responders were called at 12:21 p.m., and rescuers spent hours trying to remove the victim’s body, which police said had come to rest on a stanchion under the bridge.
Boston firefighters were able to extract her body around 4:30 p.m., and lower it onto a rescue boat. They transported the remains of the woman, whose name was not released, to a nearby marina, where the medical examiner later retrieved it.
Joyce, of the mayor’s office, said police are now the lead investigative agency for the city and will examine what kind of warnings are issued to pedestrians before the bridge is raised.
Boston police homicide detectives will be able to view video surveillance of the bridge to try to determine exactly what happened.
The bridge, which serves as a vital link between Chelsea and East Boston, was rebuilt by the Department of Transportation in the late 1990s and is inspected by the state every two years. It was inspected within the past two years, city officials said.
According to the city Department of Transportation’s website, the bridge was closed for eight hours on July 12 for unknown repairs.
Along the bridge Tuesday, stunned motorists and pedestrians tried to understand what went wrong. Many commuters said the bridge is safe and that they get ample warning before it opens.
But Bernadette Lambert of Chelsea recalled that she and her friend were crossing the bridge after midnight on Monday and suddenly panicked as they approached the break in the lift in the bridge.
“I thought, what if this came up?’’ she said. Her friend assured her that the foghorn would sound, giving them ample time to get back to safety. But she said she was not convinced. “I just didn’t feel safe. And now, look what happened — someone died,’’ Lambert said.
Globe Correspondent Jacqueline Tempera contributed to this report. Meghan E. Irons can be reached at email@example.com. Follow her on Twitter @meghanirons. John R. Ellement can be reached at firstname.lastname@example.org. Follow him on Twitter @JREbosglobe. Maria Cramer can be reached at email@example.com. Follow her on Twitter @globemcramer.