Emergency crews are searching for Charles Brennan, 16, after he was last seen leaving his home on Mulgowrie Road at Bigga about 6.30pm Friday.

A NSW Police Media spokesman said officers were particularly worried about the boy because of his autism and age.

"It’s a country area and we understand it’s fairly rugged terrain so we're concerned for his welfare, particularly if he's been out overnight," the spokesman said.

"The other thing we’re asking is if anyone has given someone in that area a lift, to a hospital or a house or anywhere, to come forward."

"Nothing is too small a piece of information."

Charles is described as about 180 centimetres tall with a skinny build and dark short hair.

He was last seen wearing a hooded jumper, tracksuit pants and no shoes.

A Maroubra boy who was reported missing after he failed to return home from his Mascot school on Thursday afternoon has been found.

Police said they discovered Garry Barrington, 11, safe and well in Waterloo.

He was taken to Maroubra police station and is expected to return home later tonight.

Anyone with information about Charles's whereabouts can phone Goulburn police on 4824 0799.