A National Grid crew working in the street at Dorchester Avenue at Ashmont Street struck a Boston Water and Sewer Commission main around 6 p.m. on Tuesday, turning Peabody Square into an impassible lake and forcing firefighters to evacuate at least one building after they started smelling a strong odor of gas.

National Grid workers apparently drilled into the main as they were searching for the source of a natural-gas odor that had been wafting through the area since at least Sunday.

By the time BWSC workers arrived on scene shortly after 6:30 p.m. to stanch the flow of water, the flooding had left a 9-foot-by-9-foot flooded hole in the middle of the square.

Police shut Dorchester Avenue through the square, along with streets feeding into it, such as Bushnell Street at Lombard Street. State Police were asked to shut Dorchester Avenue at Gallivan Boulevard.

The flooding did not reach the nearby Ashmont Red Line stop, but it did cause delays on the Ashmont branch.

Boston firefighters, National Grid workers await the arrival of BWSC crews to stop the flooding:

The calm after the torrent stopped: