Police are responding to a serious incident in Worthing town centre.
Officers have sealed off Upper High Street and a number of emergency vehicles can be seen at the scene.
Forensic officers are also there, an eyewitness said, and a crime team.
Police officers are going door-to-door, the eyewitness said.
A spokesman for Sussex Police said officers were responding to a 'public order' incident. He could not confirm any more details at this stage.