PORT ALLEN - A four-mile long traffic jam was caused by a trailer-full of startled race horses after a mishap with the animals' trailer Monday. 

Click HERE for WBRZ's live traffic map.

Watch WBRZ News 2 at 4:00 and 5:00 for live traffic updates: Stream the news here.

Authorities said the trailer became detached from the vehicle towing it and wobbled around the interstate until it came to a stop near the top of the I-10 Mississippi River Bridge around 3:30 Monday afternoon.  The horses were not hurt but were so startled, they were not cooperating with handlers trying to move them into another trailer.

Traffic was backed up for more than four miles on I-10 East into Baton Rouge as emergency crews closed most lanes of the bridge approach to deal with the situation. The bridge has since reopened.