THE Army Jetty on Rottnest Island has partly collapsed, trapping one person who was freed by people responding to the emergency.
At least three people, possibly four, were fishing from the jetty on Wednesday morning when the collapse occurred.
One person needed to be rescued after their foot became trapped, while at least two other people made it safely to shore.
Police are trying to confirm if a fourth person was also caught up in the incident. That person is believed to be safely ashore.
The extent of any injuries is not know but they are believed to be minor.
The collapse occurred at about 6.22am at the Army Jetty, which is south of the main ferry jetty near the old army barracks in Thompson Bay.
Police say a multi-agency response to the incident has begun, including deployment of the RAC Rescue Helicopter, and Water Police vessels from Fremantle.