Grammar usage

Sorry, but I can't quite agree with Koshik.

'Picked up' has so many different meanings that even paired with 'The officials', the meaning is not clear enough.  (The definitions below are copied and pasted from the Longman Online Dictionary, with my own original example sentences....)

'Picked up' has the following meanings -

(1) to collect something from a place - I went to the post office to pick up my mail.

(2) to let someone get into your car, boat etc and take them somewhere - I picked my wife up from the airport.

(3) to learn something by watching or listening to other people - When I spent a summer in Spain, I picked up quite a bit of Spanish.

(4) to notice something that is not easy to notice, such as a slight smell or a sign of something - She didn't say much about her marriage, but I picked up the fact that she is not so happy anymore.

(5) if a machine picks up a sound, movement, or signal, it is able to notice it or receive it - My shortwave radio can pick up stations from as far away as Russia.

(6) to become friendly with someone you have just met because you want to have sex with them, usually involving meeting them for the first time at a public place and leaving together - I went to the pub last night and picked up a really beautiful woman.

(7) if you pick up where you stopped or were interrupted, you start again from that point - After she interrupted me, I picked up on what I had been saying previously.

 (8) if a situation picks up, it improves -  My business has really picked up recently.  I am almost rich!

And there are actually a few other meanings.  But those are the main ones. So 8 different meanings, and several of them could apply to this sentence.  So it is not specific enough.

Getting back to Sanjay's original question - being taken into custody has 2 meanings, and your sentence is ambiguous, so I am not sure which meaning you intended.  It is ambiguous because it is a child.  I think children are not often arrested, so here are the options  -

(1) when someone is kept in prison until they go to court, because the police think they have committed a crime - The officials took the child into custody.

Alternative - The police arrested the child.  Or, The police put the child in jail.

(2) when someone is responsible for keeping and looking after something/somebody: The officials took the child into custody.

Alternative - The police removed the child from his/her parents' home and took/put it into custody.

-The police put the child into the custody of social services.