(CNN) -- At least 14 people were injured when a gas line in Kansas City, Missouri, exploded and ignited a four-alarm fire, officials said Tuesday night.
The explosion apparently leveled JJ's restaurant, a popular spot in Country Club Plaza, an upscale shopping district and residential neighborhood that is a regional gathering place.
Mayor Sly James said the walls of the structure had collapsed.
One witness told CNN affiliate KSHB a man who had a hand-held device came into the restaurant before the blast and told her and 10 others in JJ's to leave.
Jennifer Carter told the station that restaurant workers already had turned off the appliances because people inside had smelled gas.
She said she left when told and was a few blocks away when she heard the explosion.
Residents who live near JJ's said they reported smelling gas to the utility company about an hour before the explosion, according to CNN affiliate KCTV.
The explosion shook doors and windows at nearby businesses and homes, the station reported.
James, who came to the scene from his office, said his primary focus was the victims.
"That's the main concern, making sure they come out OK," he said, adding that the fire department was checking the gas line to make sure there aren't any secondary explosions.
Officials at three hospitals indicated at least 14 people were hospitalized, including four in critical condition and two in serious condition.
The number of injured had dropped from previous reports because there was "a lot of confusion with people coming into the emergency room." Dr. Leonardo Lozada, the chief physician at St Luke's Health Systems, told CNN.
Two patients are in critical condition at St. Luke's Hospital, said Dr. Marc Larsen. One of the patients suffered extensive burns; the other facial trauma, he said. Most of the five other patients suffered minor lacerations or inhalation injuries, he said.
James Garrett, a spokesman for the Kansas City Fire Department, said there were no fatalities at the scene, but two of those hurt had life-threatening injuries.
He said the fire had been put out.
The cause of the explosion had yet to be determined, a spokeswoman for Kansas City police said.