SHANGHAI-- A man in Shanghai was formally arrested Friday on suspicion of molesting three girls at a kindergarten, local prosecutors announced.

The man, surnamed Zhang, a migrant worker in Shanghai, is suspected of sexually assaulting the girls at a kindergarten in Yangpu District on June 7. The girls, two of whom are aged five and the other six, are the children of other migrant workers.

Zhang, who is not a kindergarten employee, was covering his wife's duties on June 7. His wife, a cook at the kindergarten, was at home taking care of their child, according to the local bureau of education.

Zhang was detained on June 11.