Traffic has slowed to a crawl on the Story Bridge and across Brisbane this afternoon following an incident between a man and police.

Police were called to the scene shortly after 2.30pm and are still speaking to the man.

At least 12 police officers are at the scene and a water police boat is in the Brisbane River below.

One of three south-bound lanes have been closed to traffic, as well as a cycle path underneath the bridge. City Cats are still operating, however.

Traffic is at a crawl across the bridge at present and motorists are advised to seek an alternate route.