LAKEWOOD, Colo. (CBS4)– There were multiple fatalities in the fiery crash at the Colorado Mills Parkway on I-70. Both the eastbound and westbound lanes were closed overnight and into Friday morning during the crash investigation and firefighting efforts.

Our crash investigation on I-70 continues. We can now confirm multiple fatalities. 6 others taken to local hospitals. Highway remains closed and will be at least overnight. — Lakewood Police (@LakewoodPDCO) April 26, 2019

On Thursday evening, investigators said there were 12 vehicles and three semis involved in the crash and fire. It was unclear what started the fire but investigators are taking a close look at a semi that collided into traffic, which started the fire.

Those killed in the fire and crash have not been identified. There were several people injured in the crash. One of those injured is a West Metro Firefighter. It is unclear the ages of those injured.

Thick, black smoke rising from the crash could be seen for miles across the Denver metro area.

Eastbound I-70 was closed from 6th Avenue to Highway 58 and westbound lanes are open with an on-off ramp detour at Denver West Parkway.

I70 shutdown in both directions at Denver West due to multiple vehicle crash. Several vehicles on fire. Avoid area. Interstate expected to be closed for several hours. State Patrol assisting road closure for Lakewood PD. pic.twitter.com/dZ9u92X5S1 — CSP Public Affairs (@CSP_News) April 25, 2019

One person driving in the area captured on video a white semi speeding past slower traffic.

What happened leading up to that semi crash is being investigated.

Copter4 flew over the scene which showed several vehicles on fire, including a semi that was hauling lumber. That wood fueled the fire, along with a semi hauling mattresses.

Denver West Parkway bridge over I-70 believed to have suffered heavy damage. Fire remains on scene as hotspots remain. — Lakewood Police (@LakewoodPDCO) April 26, 2019

Lakewood police say the Colorado Mills Parkway overpass suffered heavy damage from the heat of the fire. I-70 is expected to remain closed for several hours during the investigation and cleanup.

Assisting Lakewood PD with major crash on I-70 at Denver West. Avoid the area. Media to United Artist Theaters at Denver West. S1 pic.twitter.com/geOv0sEGii — CSP Golden (@CSP_Golden) April 25, 2019

Several agencies responded to the fire, including West Metro Fire Rescue, the Colorado State Patrol and Lakewood police.

Fire crews sprayed the burning vehicles with their hoses, which turned the black smoke into white smoke that continued to rise into the air.

There were several vehicles burned beyond recognition mixed in the debris of the lumber that spilled from a semi.

Because of the closure, drivers are urged to plan an alternate route since that portion of I-70 will remain closed into the Friday morning hours.