Detectives have arrested a man on suspicion of filming a YouTube video showing two bloodied schoolchildren fighting.

Officers from Sussex Police child protection team based in Crawley have arrested a 21-year-old man from the town.

The man walked into Crawley police station and handed himself in hours after The Argus put up 50 posters in the town asking people with information to contact the police.

The station's desk sergeant took his details and officers later rushed round to his home to interview him.

He was being questioned last night on suspicion of aiding and abetting an assault.

The sick videos appeared on YouTube seven days ago and showed two children punching, kicking, headbutting and stamping on each other while an adult goads them on.

Police have identified a 12-year-old boy from Crawley who they believe appeared in the two videos.

Last night he was being spoken to by West Sussex County Council social services.

Officers hope to identify the other boy tomorrow, who they understand is from Manchester.

Det Sgt Richard Harris said: "As a result of media coverage, he came into the front office and the officer took his details.

"We went round to his house and it became clear to us he was a clear suspect so we brought him in for questioning.

"We have identified one of the children and spoken to him with social services but we believe the other boy is from Manchester.

"We are happy we have got one of the boys but we are hoping to get the other as a result of our inquiries."

The Argus has offered a £1,000 reward to anyone with information which significantly leads to the successful prosecution of the person who filmed the sick scenes.

The videos, called Lethal Fight (Crawley) and Lethal Fight 2, were shot in a bedroom decorated in posters and teddy bears.

The boys are goaded on by the swearing cameraman, who orders them not to hug and says :"You're fighting like girls, fight properly".

At one point one of the boys looks at the camera and says: "Kicking is allowed, isn't it?"

All the time the adult filming tells the youngsters to "smack the s*** out of each other".

The cameraman laughs when one of the boys begins to cry before encouraging him to retaliate with his fists.

Yesterday, officers visited schools to ask headteachers to put up pictures of the children in an attempt to identify them.

Police need the help of YouTube to find the cameraman but last night said the California-based company had not responded to their faxes or calls.

Det Sgt Harris said: "We have left messages and are desperate to hear back from YouTube.

"There are certain legal agreements we must meet to get the information we need from YouTube.

"We must make sure we follow the correct procedures so we don't jeopardise the investigation."

Crawley's Labour MP Laura Moffatt helped put up posters printed by The Argus in her constituency and pinned one up on her office door in The Broadway.

She said: "I have watched it over and over again and it is hard to take in.

"The worst thing is the person who has filmed it shows complete naivety and doesn't seem to think he's done anything wrong.

"I'm really pleased The Argus is offering this reward and it shows the newspaper is acting in the interests of the community.

"I'm convinced with the reward the person responsible will be found and when he is something must be done."

Sussex Police will set up an online exploitation team in July to monitor websites popular with young people.

One detective sergeant and six detective constables will scour social networking websites such as MySpace, Bebo, Facebook as well as YouTube and chat rooms.

Sussex Police are still appealing for information. The Argus has edited the footage and it can be seen in the video section of this website to help people identify anyone involved.