Can the DCF or police talk to a minor without the parent's consent or knowledge?

On Friday the twins (age 9) wound up with CO poisoning due to a hole in their dad’s exhaust pipe.
They were in the car for 45 minutes.
When Dad realized something was wrong he called my daughter.
She came, took 1 look, and rushed everyone to the ER.
Apparently CO poisoning in little kids is really rare and they automatically called the police and DCF.
Today the cops and DCF went to the twins school to talk to them. Nobody said a word about it to my daughter. She’s a bit upset.
She asked if what they did was illegal.
I have a feeling it’s not, but I wanted to see what y’all know about it.