A man who was acting erratically with a shopping cart full of petrol cans and potentially hazardous material has been sent to hospital under police guard after causing part of the Australian city of Melbourne’s business district to fall into lockdown.

It was later confirmed that there were no dangerous chemicals in the trolley. However, police said the man had a cylinder that triggered the alarm.

“I can’t tell you what was contained in that cylinder, but it was sighted, and that initiated police response,” Acting Senior Sergeant Bonnie Heazlewood told reporters.

Investigators arrested a 52-year-old man who lives in the suburb of Kurunjang following a 45-minute negotiation at a building on the corner of William and Bourke streets early on Sept. 20.

A witness said in comments obtained by AAP that the man appeared to be pushing a trolley with chemicals, while another witness said he smashed tiles on the ground and claimed to have asbestos in hand.

Police initially reported that the man possessed petrol cans but later confirmed they only contained water.

“There’s been no property damage and no injury to any persons at this stage,” Acting Senior Sergeant Heazlewood said.

“We took the initial response for the public’s safety, which resulted in a temporary lockdown of the city.

“It’s an isolated incident. It wasn’t something that was premeditated.”

Fire Rescue Victoria said the incident was under control at 8:15 a.m. after firefighters at the scene concluded that there was no fire risk.

Witnesses Sam Di Palma and Daniel Safstrom said they were buying coffee when they saw police officers trying to talk to a man carrying a trolley inside the building.

“A bloke (was) behind a counter with a trolley full of chemicals or explosives,” Di Palma said in comments obtained by AAP.

Safstrom said the police sent one officer in to sit down and negotiate, and both of them grabbed a chair.

“I’m a bit shocked, to be honest. It’s something different,” he said.

Another witness, Abraham Elosman said the incident reminded him of the Bourke Street Mall attack in January 2017, where a man drove a stolen car into pedestrians in Melbourne CBD.

“I thought maybe they were doing an exercise or something. I didn’t think there was gonna be this big issue,” he said.

“But when I saw the shields and the fire brigade come in, I was a bit worried. I thought ‘I hope it will be OK’.”

The locked-down area has been reopened to the public after police declared it safe.