Strange accident/goings on 696 Michigan This Morning

I get a rambling call from my wife who was going Westbound on 696 in Detroit, from Warren to Livonia.

She said from 75 juction, onwards there was a strange black smoke wafting over the freeway from the North.

When she Arrived at Greenfield they were placing plastic pieces of something or another onto flatbed trucks and there was a black, unmarked helipcopter. Police were routing everyone off the expressway onto the service drive.

I can't find anything about it on the internet/local news websites.

Anyone know anything about this? Sounds strange.