A staff member of Chongqing Zoo takes care of two pairs of newborn giant panda twins at an outdoor naming ceremony in southwest China's Chongqing Municipality, Sept. 30, 2019. The two pairs of giant panda twins, born on the same day by their mothers Lanxiang and Mangzai on June 23, were named Shuangshuang, Chongchong, Xixi and Qingqing respectively at Monday's ceremony. (Xinhua/Tang Yi)

CHONGQING, Sept. 30 -- Four newborn giant panda cubs made their first public appearance on Monday at the Chongqing Zoo in southwest China.

The cubs, two pairs of twins, were all born on June 23, a rare case in the breeding history of captive pandas in the world.

Their names are Shuangshuang, Chongchong and Xixi, Qingqing, combining to symbolize "double joy and happiness" in Chinese.

The four cubs have been growing well, with Shuangshuang being the heaviest at 5.8 kg and Xixi the lightest at 4 kg, said Yin Yanqiang, the giant panda technical supervisor with the Chongqing Zoo.

Starting Monday, tourists can watch the cubs outside the window of the cub nursery from 10:30 a.m. to 11:30 a.m. and from 1:30 p.m. to 2:30 p.m. every day, according to the zoo.