Amid growing concern over waning public knowledge of wartime tragedy, a memorial service to mark the 56th anniversary of the Great Tokyo Air Raid was held Saturday at a park in Tokyo's Sumida Ward.

Survivors and relatives of the victims gathered at a memorial hall in Yokoami-cho Park, which was originally built in 1930 to commemorate the victims of the 1923 Great Kanto Earthquake.

The remains of about 105,000 air raid victims and 58,000 quake victims are stored inside a charnel house that is combined with the quake hall.

About 400 relatives attended the annual Buddhist style service, while many others visited the park to offer flowers and incense at open air stands.

Tokyo Gov. Shintaro Ishihara said it is hard to find evidence of scars left by the air raid in today's Tokyo and that people's memory of the incident is waning.

"But we should not forget that the peace and prosperity of Tokyo today is built upon the sacrifice of the victims."

Tokyo was repeatedly targeted by U.S. air raids in World War II, with the most deadly occurring in the spring of 1945.

The incendiary attack during the early hours of March 10 targeted the capital's "shitamachi" district -- a densely populated area of traditional working class communities.

An estimated 100,000 civilians died in the attack, 270,000 buildings were destroyed and 1 million were left homeless.

Fusako Ishikawa, 77, said she has not missed the service for more than 30 years. "They died in the heat. I hope at least they are living happily in heaven," she said.

"I hope the memory of the tragedy continues to live on," said Ishikawa, who lost her younger brother in the raid. "I tell my son to keep attending the services after I die."