Autistic teenager William Callaghan has been found alive and well after going missing on Monday morning in thick Victorian bushland.

He was found by one of 450 volunteers looking for him at Mount Disappointment, north of Melbourne.

The non-verbal autistic 14-year-old was carried by his mother, Penny Callaghan, and her partner Nathan Ezard from the car to the paramedic station for treatment.

Despite the excitement of the volunteers, they were told not to applaud when William arrived as it would overwhelm him.

He was found by a bushwalker who spotted William standing and smiling in the bush.

He was located just hours after his mother pleaded for those in the area to help find him.

“We are desperately hoping he will be found today,” William’s mum Penny told media this morning.

“He has an intellectual disability and, um, he’s very smart in his own way, you know? I’m feeling positive because he’s quite resilient. He is very skinny.

“He doesn’t have much padding on him, but he eats all the time, he’s always on the move. He’s very active, so he’s quite fit.”

The Victorian Police force were also thrilled by the news, as he had spent two nights in near-freezing conditions.

“When you have someone out lost in the bush, we are fighting against time,” Search and Rescue Squad Senior Sergeant Greg Paul told reporters on Tuesday.

“It can take a long time to find someone if they are lost in this terrain.

“We all have limitations, this time of year especially. There is no sugar coating it, it is life-threateningly cold.”

A volunteer told news.com.au  that there were scenes of “absolute jubilation” among those who saw Will after spending hours looking for him in the harsh Victorian bushland.

“We just saw Will,” she said. “He looks in really good shape. He smiled at everyone as he was lifted out of the car.”