KANSAS CITY, Mo. (AP) — A day after a natural gas explosion leveled a popular restaurant, investigators raced to search the rubble and tried to understand how the blast happened despite suspicions that flammable fuel had been leaking, maybe for weeks, somewhere in the busy outdoor shopping area.

Hours before the explosion, witnesses reported a strong smell of gas, and firefighters were summoned to the scene at one point but left without ordering an evacuation.

As the cleanup got under way Wednesday, search-and-rescue crews recovered a body. Mayor Sly James declined to identify the victim, but the mother of a missing restaurant server said her family was awaiting confirmation that the remains were those of her daughter.

More than an hour before the blast, a subcontractor working for a cable company hit a gas line with underground boring equipment. Then something inside the restaurant ignited the fuel, authorities said.

Surveillance video from a nearby travel agency shows a fireball erupting from the restaurant's roof, showering the street with debris and throwing up a cloud of dust and smoke. The blast could be felt for a mile and shattered glass in neighboring buildings.

Fifteen people were injured. Six were still hospitalized Wednesday, James said.

People who live and work in the area reported smelling gas for some time before the accident.

Jeff Rogers was waiting at a bus stop down the street from JJ's when the explosion knocked him and another man to the ground.

He said he had smelled gas — although "not strong" — at the intersection for the past couple of weeks. Then the odor intensified Tuesday.

William Borregard, who lives with his sister and her fiancé in the apartment building nearest to JJ's, said he too had noticed a strange smell for weeks that had worsened in recent days. On Tuesday, they called the apartment manager.

"We said, it's very pungent and you should come out here and check it out," he said. "He came over and rapped on the door and said there's nothing to worry about. Stay in your apartment." The blast happened five minutes later.

Dr. John Verstraete, a physician who works at a medical practice next to the restaurant, told The Kansas City Star that some office employees smelled gas for several hours Tuesday afternoon. The smell grew stronger through the day.

But no one alerted the Fire Department or utility officials to the possibility of a leak until the subcontractor called 911 shortly before 5 p.m. Tuesday to report having ruptured the gas pipe, the mayor said.

Within 20 minutes, a worker for Missouri Gas Energy arrived at the scene, followed later by a backhoe to dig a hole that would allow the gas to vent into the air, MGE Chief Operating Officer Rob Hack said.

Those who remained in the restaurant were urged to leave, Hack said. A gas company employee urged people to evacuate the medical center, too.

The blast happened around 6 p.m. Tuesday, when the dinner crowd would have been filing into JJ's and the many other restaurants in the upscale Country Club Plaza shopping and dining district.

The restaurant was a fixture on the city's culinary scene for more than 27 years. Locals knew it as a prime after-work stop, though it won a broader reputation after receiving consistently high ratings from contributors to Zagat's restaurant guides, both for its food and its long wine list. Continued...