Phrases such as It is said, it is believed, It is thought ... are impersonal passive constructions. We often use them in news.
Passive sentence - version 1: passive + that + clause
It is said that children are afraid of ghosts.
Passive sentence - version 2: passive + to
Children are said to be afraid of ghosts.
The correct active sentence would be:
Active sentence: People say that children are afraid of ghosts.
To get some practice click HERE.