Lai Wing-kit, a 26-year-old man who led a group of about 500 people from Hong Kong to attend the ceremony, said he was saddened by what he saw.

"The ceremony and the hall make people remember history and think about the crimes that wars can bring," Lai said.

Liu Ke, a middle school teacher from the Sun Fong Chung College in Hong Kong, attended the ceremony with eight students.

Liu, who is in his 20s, was born and raised on the mainland, and received his higher education in Hong Kong. He said many of his students had limited knowledge of the massacre.

"Personally, I feel it's very important for students in Hong Kong to attend this event. It's very important for them to learn about the past," Liu said. "Teenage students in Hong Kong know very little about the Nanjing Massacre."

Tsou Ying-yen, a 16-year-old student at Liu's school, was among the 400 students attending the ceremony.

"I don't know much about the Nanjing Massacre and there was little in the schoolbooks," she said. "But I know that more than 300,000 people were killed, and that 20,000 women were raped."

According to Liu, more than 400 students and teachers from 11 schools in Hong Kong attended the ceremony after being invited by the Nanjing city government.

Students arrived in Nanjing on Wednesday, and will stay on the mainland for a week to attend joint activities with middle schools in Nanjing and Shanghai. The activities will help students learn about the Japanese invasion.

"Seventy-five years have passed, and only about 100 survivors from the massacre are still alive," Liu said. "It's increasingly necessary for the younger generation to learn about the past, so that they can tell their peers and future generations."

Qian Jieyi, a 22-year-old Nanjing resident, said she visits the hall every year on Dec 13.

"We should hope for peace, not hatred. China and Japan need to make a joint effort to reach a good relationship," Qian said.

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