A homeless man only known as Dave says he ran into a burning Darwin insurance office to drag out a woman who was trapped inside.

The TIO office, which is located in Darwin's Woolworths complex, was firebombed on Wednesday morning.

Witnesses described seeing thick smoke and fire inside the office.

A 45-year-old man called Bird today faced Darwin Magistrates Court charged with nine counts of attempted murder as well as several other charges.

Nineteen people were hospitalised after the incident, including four who remained in hospital today.

Dave said no-one else would go into the burning office so he told them to move aside.

"I was sitting there in front Woolworths, just waiting to get in, and I heard the explosion," he said.

"And I went racing ... and they reckoned there was still a girl in there.

"So I said, 'Get out of the road, you bastards', because nobody would go in."

"I managed to get her out ... I dragged her out."

He said the woman was rushed to hospital in an ambulance, but he has seen her since.

"She came back the day after and said, 'You're the bloke that pulled me out, because no-one else would go in because of the smoke'."

Dave said he has not been to hospital because he does not want to burden staff who are dealing with victims of the blast.