A security guard has described a terrifying ordeal after an arsonist tried to torch his car with him still inside during a firebomb attack at a tobacco warehouse in Adelaide.

Hassan Zahid was keeping watch over the building on Beulah Road in Norwood when a van exploded in flames at 6.30am, sending black smoke and bright orange fumes into the air.

WATCH THE VIDEO ABOVE: Security guard escapes arson attack at warehouse

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Zahid says he spotted the suspect wandering around about an hour before the attack.

“He was at the front door of the building, so I just rolled down my car’s window and I was like, mate, you can’t be here,” Zahid said.

“So he was holding a blue jerry can with him and I was 100 per cent sure that he was here to burn down the place.”

The blaze broke out on Saturday morning. Credit: 7NEWS

The man walked off but soon returned with what appeared to be flammable liquid.

“He was holding approximately two-ish litre of flammable liquor, you can call it. I saw him opening the bottle’s cap and throwing the liquid at my car,” Zahid said.

“I instantly just started my car and just drove off due to my safety.”

He says the suspect then jumped a fence and threw Molotov cocktails at the van.

“It was horrific, it was like bizarre that I couldn’t even imagine it,” he said.

Hassan Zahid said it was horrific. Credit: 7NEWS

It’s the third arson attack at the tobacco warehouse since April.

The locksmith next door, Steve Clark, says he’s thinking about moving his business if the arson attacks continue. One of the firebombs hit his building by mistake.

“We might have to move. It’s a bit bloody scary and yeah, we were hit and I don’t want to be hit again,” Clark said.

Detectives are looking at CCTV to try and identify the suspect.