Rescue teams with cadaver dogs are searching through the rubble of a Kansas City restaurant after a gas explosion sparked a massive blaze.

At least 14 people were injured in the fire in an upscale shopping district in the city in Missouri, which completely destroyed JJ’s restaurant.

No fatalities were immediately reported but authorities urged caution.

Fire Chief Paul Berardi said several patrons were likely inside the restaurant when it went up in flames, and cadaver dogs were brought in to help sift through the charred debris.

“We are concerned that there may be additional people that were not able to get out of the structure,” he said, adding that the blaze erupted during happy hour.

“I would always fear there are fatalities in a scene like this.”

He said results of the search would take hours.

The blaze occurred shortly after 6pm local time.

Images showed dozens of firefighters battling the blaze that spread through a number of buildings including shops, restaurants, flats and offices.

The manager of JJ’s restaurant said earlier that three people were unaccounted for. But it was unclear whether they were caught in the blaze or had left earlier.

City Manager Troy Schulte said it appeared an accident by a utility contractor had caused the blast, and a statement from utility Missouri Gas Energy late Tuesday reiterated that possibility.

Mr Berardi said there had been reports of a strong smell of gas before the fire, but he stressed the cause was still being investigated.

St Luke’s Hospital was treating eight people, including one who had suffered extensive burns, officials said.

The University of Kansas Hospital was treating six people injured in the blast, including one in serious condition, according to spokesman Bob Hallinan. They had all suffered traumatic injuries, including broken bones, rather than burns or smoke inhalation.

The shopping area was established in 1922 by J.C. Nichols. Based on the architecture of Seville, Spain, it includes retail shops, restaurants, apartments and offices.

Watch Kansas City  JJ’s Restaurant massive fire video

[media id=834 width=610 height=340] [adrotate banner=”46″]