DARWIN, Australia (AP) -- A disgruntled customer wheeled a shopping cart loaded with gasoline-filled jerry cans and lit fireworks into an Australian insurance office Wednesday, causing a blast and fire that injured 15 people, authorities said.
The attack triggered temporarily panic in downtown Darwin, the biggest city in the vast swath of Outback in Australia's north known as the Top End.
Witnesses described a large booming noise and sounds like gunshots going off, before seeing smoke billowing from the building and people stumbling out. Part of the city near the site of the attack was cordoned off as emergency crews arrived and an investigation was launched.
Police said 15 people were treated in a hospital for burns and smoke inhalation, including one officer. Police Commander Colleen Gwynne said four of the victims were in an intensive care unit while the rest were being discharged.
A 44-year-old man was taken into custody after giving himself up to police soon after the blast, which went off in the Territory Insurance Office that is part of a busy shopping complex in Darwin.
The man was being questioned but charges were not immediately filed.
"I can confirm he was a dissatisfied claimant," Gwynne told reporters about the attacker. "This is not a terrorist incident."
Fire brigade officer Dave Lines said it appeared someone had pushed a shopping cart with three cans of gasoline and some fireworks into the building. A fire had taken hold after the blast, but was suppressed by the building's sprinkler system and extinguished by firefighters, he said.
Richard Harding, the insurance company's CEO, said it had received no threats or warnings before the explosion.
He told reporters he was disturbed that the alleged attacker was an unhappy customer, but said he did not know the details of the man's claim.