NANJING, Feb. 18 (Xinhua) -- Four people were confirmed dead after three cargo boats caught fire on the Yangtze River, China's longest waterway, late Friday night, authorities said Saturday.

Flames engulfed three boats near the Jiangxinzhou Islet off Nanjing, capital of east China's Jiangsu Province, at around 11:20 p.m., sources with the city's fire prevention bureau said.

The flames were extinguished by 1:30 a.m. Saturday.

All the 12 crew members on board the boats fell into the water. Four died and the other eight were rescued, a spokesman with the city's maritime bureau said.

He said the cause of the fire was under investigation and there was no report of water pollution yet.