Media playback is unsupported on your device Media caption Amateur video captured a fire at the firework display

More than 50 people have been injured by an explosion at a summer fireworks festival in Japan's Kyoto prefecture.

Among the seriously hurt was a 10-year-old boy who was taken to the intensive care unit, fire-fighters said.

The blast happened at about 19:30 local time (10:30 GMT) on Thursday at a viewing venue in Fukuchiyama, before the fireworks were due to start.

Local media said 59 people were take to hospital, with 19 in serious condition.

Five of them were very seriously injured, Kyodo news agency said.

Festival-goers reported hearing a loud sound.

"I heard a bang and then saw a billow of smoke," said one 37-year-old man who had been volunteering near site of the blast, Kyodo reported.

The organisers of the fireworks said propane gas cylinders used at food stalls may have exploded.

The annual event, attended by 110,000 people last year, was then cancelled.