WALKER - Traffic backed up Wednesday morning on I-12 eastbound after an 18-wheeler hit an Acadian ambulance as medics responded to a call on the road shoulder.

Around 7 a.m. WBRZ traffic cameras captured the backup on the interstate near the Walker exit.

A man called for an ambulance after experiencing chest pains. Porter Taylor with Acadian said the man pulled over on the road shoulder, and crews reached him, despite safety concerns.

"Apparently, the gentleman felt like he couldn't drive anymore and pulled over on the shoulder of the interstate," Taylor said. "We tried to get him out of his vehicle as quickly as possible, into our ambulance."

During the response, Taylor said an 18-wheeler crashed into the ambulance and a fire truck at the scene.

“The whole back-end was smushed into the back of the ambulance,” Taylor said.

The inside of an ambulance is a cramped space, especially during a medical call. Taylor said that during a crash, medical supplies inside the ambulance can shift around. He says one of the medics watched as the crash happened.

“She actually saw it coming, and yelled, ‘Lookout,’ and that's when the 18-wheeler hit them,” Taylor said.

Officials with the Walker Police Department are trying to put the pieces of what happened together.

“The driver of the tractor-trailer has provided us with a couple of different explanations as to what happened,” John Sharp with the Walker Police Department said. “You've got to kind of sift through the evidence there.”

Five people were injured, including medics. Taylor says one of them lost consciousness for a moment. The medics and the initial patient were all taken to the hospital.

Officials with the Walked Police Department said charges are pending for the tractor-trailer driver.