Accident on Storrow Drive...anyone have details?

This morning on Storrow Drive I passed what appeared to be an awful accident in the tunnel that shuttles commuters to 93. Ever since the big dig tunnel collapse over a month ago I've felt a bit uneasy on my daily commute. To my knowledge subsequent investigations into the collapse found that whatever unstable epoxy was used in that tunnel has been used in tunnels all over boston to secure ceiling panels and exhaust fans weighting in excess of 1 ton.

The only visible evidence of the accident this morning from outside of the tunnel were the multitudes of emergency vehicles screaming down Storrow and one of the large green metal highway signs swinging off its hinge in the entrance to the tunnel. Either something in the tunnel (or falling from the tunnel) caused the accident, which I imagine in turn caused the highway sign to unhinge or the impact resulting from the accident caused it. Emergency personnel were handing down stretchers from the bridge above the tunnel to personnel standing at the entryway to the tunnel.

I haven't been able to find any information by radio or on the internet about this morning's incident.