BEIJING - Sirens wailed Sunday morning in cities across China to observe the 80th anniversary of Japan's invasion followed by a 14-year occupation.

Sirens began sounding at 9:18 am and lasted for three minutes in Shenyang, capital city of northeastern Liaoning Province, where the Japanese army started its assault.

More than 1,000 people from the central and local governments, the People's Liberation Army (PLA) and various walks of life gathered at the square in front of the "September 18 Museum" in Shenyang as part of the routine activities that began in 1995.

Two minutes ahead of the air sirens, bell ringers struck a bell at the museum to remind people of the national humiliation.

"We young people shouldn't forget the past. Instead, we should draw lessons and strength from this humiliating history," said bell ringer Tong Siqi, a junior at Shenyang Normal University.

"When the bell rings and the sirens sound, I believe that every Chinese will be struck inside their hearts. The history of September 18 Incident told us that we young Chinese should use our knowledge to build our nation into a strong one to avoid wars and disasters, " Tong said.

As the sirens wailed, all automobiles on the streets of Shenyang pulled over and blew their horns to join the sirens.

After the sirens stopped, a national flag was raised at the square and people swarmed into the museum to have a close look at the historical remains and pay their tribute to those who sacrificed in the fight against Japanese invaders.

On September 18, 1931, Japanese forces attacked the barracks of Chinese troops in Shenyang, marking the beginning of the Japanese invasion and occupation that lasted 14 years.

Similar memorial activities were staged in other cities across China, including Beijing, Changchun, Harbin, Dalian, Xi'an, Hohhot, Nanjing and Haikou.

In Harbin, capital city of Heilongjiang Province, sirens wailed 10 minutes starting from 9 a.m. to remind people of the historical incident.

"Although the incident happened 80 years ago, we will never forget that history of humiliation, which reminds us of cherishing peace and building China into a powerful nation," said a retired worker, He Zhicai, as he stopped his pace at the Wanda Square in Harbin to observe the sirens.

In Nanjing, capital city of eastern Jiangsu Province, historians and intellectuals held a seminar on the September 18 Incident and discussed its influence over China and Japan.

In Hainan Province, a photo exhibition was launched in the provincial library in the capital city of Haikou to display to the public the pictures and documents that record this period of history.

A Japanese tourist, Kazufumi Ishiki, 49, said he knew it was the 80th anniversary of September 18 Incident.

"I fully recognize this part of history, and I think Japan and China should now get along peacefully and unite together," said Ishiki, who is visiting Beijing on a seven-day tour.

A grand memorial activity was also staged on the Internet, which instantly became the hot topic of the day on the Twitter-like social website Weibo by Sina.com.

As of 3 pm, the topic under the name of "80th Anniversary of September 18 Incident" has attracted nearly 1.2 million mixed remarks, mostly from the country's web-savvy younger generation.

A web user with screen name of Dan Dan said, "We should never forget those heroes who sacrificed their lives for our nation and we should recall them on this special day."

Another web user, Zhou Yujie (screen name), asked," What special day is it today? Why have the sirens been sounding?"

The People's Daily, the official newspaper of the Communist Party of China (CPC), published an editorial under the title of "Never Forget National Humiliation, Join up for National Renaissance" on Sunday, in memory of the incident.

The editorial says that the incident marked an awakening for the Chinese, who commenced the 14-year war against the Japanese and won the first overall victory over foreign invaders in China's modern history.

The editorial then urges all circles in China to unite and form a "powerful, resultant force" that is necessary for achieving the national revival.