NANJING - Police in the city of Huai'an in east China's Jiangsu Province announced Tuesday that they have arrested seven people and seized more than 6,000 weapons in a major case involving the illegal manufacture and sale of firearms.

The arrests resulted from a tip received from an Internet user on March 19 alleging that a netizen using the screenname "dahaimoxing" had been selling firearms online by passing them off as replicas of actual weapons.

After confirming that the weapons were capable of injuring people, local police launched an investigation and arrested "dahaimoxing," actually a man surnamed Chen, in the city of Shenyang in northeast China's Liaoning Province in late March.

After examining Chen's computer in an effort to track down his suppliers, police found evidence that a man surnamed Wang had been supplying Chen with the weapons.

Police seized 23 guns at Wang's residence in the city of Shantou in south China's Guangdong Province in April, as well as another 5,400 guns in an abandoned factory that served as a warehouse for Wang.

The investigation then led police to another suspect surnamed Xu who had supplied Wang with weapons. Police found that a criminal organization led by Xu produced about 20,000 weapons from August 2011 to April 2012, earning profits of 1.7 million yuan (about 270,000 U.S. dollars) by selling them.

The investigation is still under way.