This story was updated at 2:40 p.m.

U.S. 23 is shut down in south bound lane due to at a massive pile up that involves at least seven jackknifed semis and up to 40 cars. North bound was previously closed, but has reopened according to Michigan State Police.

The crash occurred just before 1 p.m. on U.S. 23 near Willow Road near Milan. The location is between the Willis Road and Carpenter Road interchanges. Southbound has been closed between Willis and Plank Road and will remain closed for the next several hours.

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A long backup could been seen from the overpass at Willow Road and at least three semis could be seen partially off the road and in the median. One or two cars could also be seen in the median.

Pittsfield Township fire chief Sean Gleason said there were whiteout conditions in the area when crews arrived.

Huron Valley Ambulance confirmed the highway is closed in both directions making it somewhat difficult for emergency crews to get to the scene.

"We have emergency response en route and many on the scene already," said Karen Gabrys, with HVA public affairs. "We're directing emergency responders."

Traffic backed up on U.S. 23 on Friday January 9, 2015 after several semis jackknifed and a massive pileup occurred. Nicole Hester | The Ann Arbor News

Gabrys confirmed ambulances and a rescue helicopter are on their way to the scene. Rescue crews from Milan and Pittsfield Township also are responding, in addition to Michigan State Police.

Several fire trucks, police cars and an ambulance could be seen as well. A few people were out of their cars and walking around.

Gabrys said one person has been extracted from a vehicle and another person was possibly trapped in a semi. However, other extractions are possible once crews arrive on scene.

Although she could not confirm from the scene, Gabrys said an amputation may be necessary for one victim.

"We're still trying to figure things out on the scene," Gabrys said. "It's still very much in progress and will probably be going on for a long time."

One injured person refused treatment at the scene according to Gabrys, but did drive themselves to a local hospital.

Gabrys said the highway will likely be shut down for a long time as crews work to tend to patients before cleaning up the actual crashes.

"Our first priority is to clear patients from the vehicles," Gabrys said."It will be an active scene for a long time."

This story will be updated as information becomes available.

Ann Arbor News reporter Lindsay Knake contributed to this report

Matt Durr covers Ypsilanti for The Ann Arbor News. Email him at mattdurr@mlive.com or follow him on Twitter.