Five floors of the multi-storey car park came down unexpectedly during work to clear the site to make way for a £30m library for South Essex College.
Local residents told the Southend Standard that rubble fell into the streets as scaffolding was dislodged.
One said: “There was a massive explosion. It felt like an earthquake. Out the back it was thick with dust. All the scaffolding had buckled outwards.”
Demolition contractor Elvanite is working with structural engineers to discover what caused the collapse.
Southend Council’s strategic projects manager, Mark Murphy, said: “There was a collapse involving five of the floors.
“In accordance with health and safety requirements, the site is fenced off by safety netting and scaffolding. This largely contained the effect of this incident, and because of it, no one was injured and there was no damage to vehicles or other buildings.”
The picture of the collapse is courtesy of Demolition News