A giant kite weighing three-quarters of a tonne crashed into a crowd of spectators in Japan at the weekend, an official said Monday, hurting four people, including an elderly man.

The bamboo-framed kite measuring 13 metres (43 feet) by 12 metres and weighing 700 kilogrammes (1,540 pounds) was being flown by a big group of people at a park in Higashiomi, central Japan, for the annual “Big Kite” festival on Sunday.

It was at a height of around 200 metres when it suddenly plunged from the sky into the crowd, the official from Higashiomi city official said.

The huge kite hit and seriously injured a 73-year-old man, who remained unconscious in hospital on Monday, the official said. Three other people, including a seven-year-old boy suffered injuries.

Police have launched an investigation into the case on suspicion of professional negligence, local media reported. Giant kite festivals are not uncommon in Japan, and there have been previous cases of spectators being injured. In 2004, eight people were hurt when a one-tonne kite smashed into a crowd in Kanagawa, near Tokyo.