By Gwladys Fouche
NESLANDET, Norway (Reuters) - Norwegian teenagers at a lakeside summer camp fled screaming in panic, many leaping into the water to save themselves, when an attacker dressed as a policeman began spraying them with gunfire.
Police said at least 10 of the youngsters, attending a camp run by the governing Labour Party, were killed in Friday's attack, shortly after a blast in the capital Oslo killed seven people in Western Europe's worst bombing since 2005.
"I just saw people jumping into the water, about 50 people swimming toward the shore. People were crying, shaking, they were terrified," said Anita Lien, 42, who lives by Tyrifjord lake, a few hundred meters (yards) from Utoeya island, northwest of Oslo.
"They were so young, between 14 and 19 years old," she said.
Utoeya is an island about 500 meters long, clad with pine trees. Lien said the shooting sounded like automatic gunfire.
A camp guard, Simen Braenden Mortensen, said that the gunman had tricked his way onto the island by posing as a policeman driving a silver grey car.
"He gets out of the car and shows ID, says he's sent there to check security, that that is purely routine in connection with the terror attack (in Oslo)," Mortensen told the daily Verdens Gang.
"It all looks fine, and a boat is called and it carries him over to Utoeya. A few minutes passed, then we heard shots," he said.
A teenaged boy who witnessed the attack from the mainland told Britain's Sky Television: "We heard people screaming, it was horrible...Some were waving at us from the island."
Police said they had found undetonated explosives on the island. They said the gunman, whom they described as ethnic Norwegian, may also have been involved in planting the bomb in Oslo.
Early on Saturday, an ambulance left the lake area, with a body lying on a stretcher inside. Cars with distraught relatives were heading to a nearby hotel hoping to meet loved ones evacuated from the island.
Police and dogs were still searching the island and lake overnight from boats and helicopters, with ambulances on standby. Searchlights slowly swept the water in the dark.
People living by the lake got into boats to try to evacuate people from the water. "I used my boat to ferry a lot of people from the island, I saw many wounded people," said a local man who said he lived in a white house by the lake.
(Writing by Alister Doyle and Anna Ringstrom, Editing by Mark Trevelyan)