PITTSBURGH (KDKA) — The traffic lights at the intersection of Second Avenue at 10th Street are still out hours after a fatal crash inside of the Armstrong Tunnel.

One lane of the tunnel is still closed as city crews work to replace the utility box that was damaged during the crash.

The SUV Barbara Ann McMillan, 57-years-old, was driving, was a mangled mess following a crash inside the Armstrong Tunnel.

It was so bad, you could see the engine from McMillan’s vehicle, sitting on the street.

McMillan was from the South Side Flats and somehow lost control inside the Armstrong Tunnel on the inbound side around 9:45 Wednesday morning and crashed her SUV into the wall. She was the only person inside the vehicle and no other cars were involved in the crash.

Firefighters tried to revive McMillan, but she was pronounced dead on the scene.

Debris was scattered all over both lanes of the tunnel.

That’s because a utility box that controls the traffic lights at the Second Avenue and 10th Street intersection, which is right outside the tunnel, was struck during the crash, knocking out power to the lights.

The SUV was towed from the scene a few hours after the crash and investigators from the Collision Investigation Unit remained on scene, trying to piece together what happened.

Investigators spoke to some witnesses, but the cause of the crash is still unknown.

The lights inside the tunnel were not affected by the accident.

Power has since been restored outside of the tunnel.

WATCH: Pam Surano Reports From Outside The Armstrong Tunnel