1.   At high tide, those tunnels fill with water rich in mineral content and empty into the creek.

2.   Giant I-beams from the buildings have punctured the subway tunnels, and the tunnels have filled with groundwater.

3.   Several wooden ties turned to charcoal, and the tunnel quickly filled with a choking, sooty smoke.

4.   The tunnel quickly filled with smoke, and power had to be cut so that firefighters could enter it safely.