A teenager opened fire at a school in southern Finland on Wednesday, shooting four people - one of them fatally - before being surrounded by police, media reports and a municipal official said. The shooter, an 18-year-old man, was still inside the Jokela high school along with some students who had not managed to escape, said Heidi Hagman, assistant to the Tuusula municipality director. She said the man had shot four people, and that "one of those shot is probably the principal." Police confirmed the shooting at Jokela high school in Tuusula, some 50 kilometers (30 miles) north of the capital, Helsinki, but said they could not give details. "Ambulances and police cars are on standby," Senior Constable Tuomi Juola told The Associated Press.