Armed police and emergency services raced to Chichester city centre with the public being told on Thursday night to keep away from the area.
It is understood that a dozen emergency service vehicles had surrounded the West Sussex city centre as police cordoned off the area.
Hazardous Area Response Team (HART) paramedics trained to go in during so-called “hot-zone” incidents also rushed to the centre.
Police ordered people to stay away from the centre after being alerted to reports of a man trying to harm himself. Sussex Police said in a statement: “The centre of Chichester was closed off on Thursday evening (April 23) as police death with a man who was threatening to harm himself. “Officers were called to North Street at 9.42am due to