CHANGSHA, July 5 -- Rescuers including firefighters and armed police are closely monitoring the situation of a dike breach in Dongting Lake in central China's Hunan Province which occurred Friday afternoon, local authorities have said.

The breach was initially about 10 meters wide but has since continued to expand. The relocation of approximately 5,000 residents of the affected area has been completed, according to the local flood control department.

A large amount of lake water has overflowed from the gap with a fast flow rate, according to the government of Tuanzhou Township, Huarong County under Yueyang City.

"The breach is difficult to fix, so we advise the building of a second barrier two kilometers from the breach to contain the water," said Chen Wenping, an anti-flood expert.

Sand carrier ships have been dispatched to the scene for the rescue operation. Trucks were also deployed to fill the gap.

Dongting is China's second-largest freshwater lake. The affected area near Tuanbei Village covers about 50 square km. This area experienced a dike breach back in 1996.

Since June 16, Hunan has suffered the strongest rainfall this year, which has broken local historical records in some regions.