Police said on Monday that a man was stalking a pair of Brooklyn siblings and had left an ominous note in their mailbox.

An 8-year-old girl first noticed the man following her as she and a friend walked to a bus stop on Friday. He was hiding in between cars and ran off when the girl got to the bus stop, where several other parents were.

Then, her 12-year-old brother encountered the same man when he flagged down the school bus and tried to pick up the boy. The bus matron refused to let him do so and threatened to call the police.

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That night, the man continued to harass them both by taking pictures on the steps of their home. He asked the girl where she slept and who she lived with, but she refused to answer his questions and ran away from him.

On Saturday, the man then asked her brother similar questions about where he slept.

The family then fond a disturbing note in their mailbox from the stalker: “Watch out. I am watching you!! Your daughter is cute.”

According to police, the family does not know the stalker, and authorities are asking anyone with information about him to come forward.