Firefighters respond to a blaze following an explosion that destroyed a building in Sapporo’s Toyohira Ward on the night of Dec. 16. (Video by Nobuhiro Shirai and Susumu Imaizumi. It also includes footage provided by Akihiro Chiba.)

SAPPORO--At least 40 people were injured after an explosion apparently triggered by spray-can fumes ripped apart a restaurant and realtor office here Dec. 16, forcing terrified diners to flee from a spreading fire and collapsing building.

The victims range in age from 1 to their 60s. A 33-year-old man who was in the realtor office was in serious condition with burns on his face, according to Hokkaido police.

The blast tore through the wood and plaster building around 8:30 p.m. in an area of Sapporo’s Toyohira Ward filled with many restaurants and drinking establishments, according to Hokkaido police and the municipal fire department.

Firefighters said Dec. 17 that 19 other buildings and 26 vehicles were damaged in the explosion within a radius of 100 meters, including shattered windows of a family restaurant and houses nearby.

Victims reported a stampede inside the restaurant after the blast.

“I had no idea which area exploded,” said a 28-year-old company employee from Sapporo’s Minami Ward who jumped from the second floor of the restaurant. “I was terrified.”

He injured the right side of his body and suffered cuts on his fingers.

Local authorities set up an emergency shelter for residents in the community as a precaution against another explosion. Witnesses said they could still smell gas in the neighborhood.

A 24-year-old man walking on a nearby street that night said he heard an “explosion sound louder than a thunderbolt” and saw plumes of dark smoke rising from the building.

The restaurant collapsed and was engulfed in the fire. The realtor office was flattened, police and firefighters said.

When the blast occurred, two people were inside the real estate office and nearly 40 were in the restaurant. The two-story building also housed an osteopathic clinic, but it was empty at the time.

The damage was most severe in the realtor office, according to police and firefighters.

A worker at the realtor told investigators Dec. 17 that they were using more than 100 spray cans to sterilize and deodorize the office, according to sources.

The explosion occurred after one of the workers turned on a water heater to wash up after using the spray, they said.

The customer from Minami Ward said he was drinking with three friends on the second floor of the restaurant during the blast.

He said the lights suddenly went out, the place was filled with the smell of gas, and then the restaurant burst into flames.

He said he relied on the light of his mobile phone to get to the window, while other customers stampeded toward the exit and ended up falling over each other like dominoes.

Another customer, 49, who was seated at a table facing the street on the second floor with two family members, said the wall disappeared after the explosion.

The self-employed man from Sapporo’s Chuo Ward said he not only could see the street but also the sky through a hole in the ceiling apparently caused by the blast.

He said he also smelled gas filling the restaurant and then a fire that was quickly spreading.

About 20 guests were on the second level, and they rushed in his direction because the wall was gone and they were trying to get outside, he said.

But soon, the floor collapsed and he fell to the first floor.

“I thought I wouldn’t make it when I saw the fire,” he recalled.

A man who runs an “izakaya” pub-inn across the street said he looked out after hearing the loud noise around 8:30 p.m. and saw that the outer wall of the restaurant was gone.

He heard cries from the second floor before it collapsed.

Firefighters extinguished the fire amid piles of broken pillars and wooden pieces.

The site is about 3 kilometers southeast of the center of Sapporo.