Four residents of Xuzhou county, Jiangsu province, were injured by an exploding balloon that may have floated 350 km from Zhengzhou, Henan province, Modern Express reported on Wednesday.

According to a woman surnamed Qin, a farmer in the county, the balloon, believed to have been filled with hydrogen, was found in her courtyard at about 4 pm on Feb 15 when she returned home with her two nieces, aged 2 and 4. “My nieces were attracted by the red balloon, which was 1 meter in diameter, and ran to it, but it suddenly blew up and injured the two kids, as well as my 10-year-old daughter and my 62-year-old father who were standing nearby,” Qin said.

Qin said she found a banner under the balloon with the words, "Bank of China Zhengzhou branch", so wondered if the balloon floated from Zhengzhou, a city some 350 km away.

The four injured people were taken to a hospital and Qin's two nieces are still in serious condition. The county police went to Zhengzhou to investigate the case.