GREEN BAY — UPDATE — A tour bus carrying 54 passengers crashed while exiting I-41 northbound onto Webster avenue.
33 people are injured, two people with critical injuries, according to the Green Bay Metro Fire Department.
GMFD said many of the passengers were elderly.
The remaining passengers were transported on a separate bus to Krok Community Center.
The Green Bay Fire Department said at one point, no medical units were left in Green Bay, and neighboring Luxembourg, Ashwaubenon and De Pere provided resources.
"You're calling in resources to help you out and that goes into our mutual aid box alarm system," Fire Chief Chad Bronkhorst said. "It worked flawlessly."
The bus was taking passengers from Chicago to a casino in Michigan, and while exiting I-43 went through an intersection and down an embankment.
The cause of the crash is under investigation.
State patrol is investigating the vehicle for potential defects.
Green Bay police says there's a video of the crash from a following vehicle.
"What happened isn't really up in question, it's why it happened, and we don't have the answer for you right now," Captain Clint Beguhn with GBPD said at the press conference.
Bronkhorst said the fire department trains for these exact situations, and the response went smoothly.
"Our personel did a fantastic job," he said.
If you think you might have a loved one that was on the bus, GBPD said to call 211.
Watch the Sunday night broadcast story here:
GREEN BAY — A tour bus with 54 passengers crashed into a building off of I-43 in Green Bay near Angie Avenue, Mutual Aid Box Alarm System (MABAS) Wisconsin announced on Sunday afternoon.
Between 15 and 20 patients sustained non-life-threatening injuries, according to MABAS.
A box 4-13 to 2nd Alarm Levels was called for additional EMS units as well as nearby hospitals have been notified.
People on the bus told NBC 26 they were traveling from Chicago to Harris, Mich. in Menominee County. They say the bus was traveling on I-43 when it went off the highway and eventually crashed into a building.
Photos from the scene show the location and damage to the bus.

NBC26 is working on getting more information. This article will be updated as we learn more.