Four people have been injured and one teacher killed after a masked man with a sword reportedly attacked a school in Trollhättan, Sweden.

Police told Swedish news agency TT there was "considerable confusion" at the school, which had been evacuated.

A teacher has been confirmed dead following the attack, AP reports.

Sword attack at Swedish school

A large number of police cars and ambulances are at the site of the attack, The Local website in Sweden reports.

One ambulance is reported to have crashed into the wall of the school as it arrived on the scene.

Police responded to an emergency call saying a person had been attacked at, or near, the Kronan school cafeteria.

"We have a number of people injured," Stefan Gustafsson, from the region's police force, said.

In pictures: Sweden school attack Show all 5 1 /5 In pictures: Sweden school attack In pictures: Sweden school attack Emergency services at the scene of the attack in school in Trollhattan Rex In pictures: Sweden school attack Swedish police officers at the scene of the attack Getty Images In pictures: Sweden school attack Police react outside the school in Trollhattan, as a masked man with a sword attacked students and a teacher In pictures: Sweden school attack Swedish police officers secure the area outside a primary and middle school in Trollhattan Getty Images In pictures: Sweden school attack Swedish police officers secure the area outside a primary and middle school in Trollhattan Getty Images

He confirmed officers had shot a man.

"What exactly it is about, we have no answer to right now," Mr Gustafsson added.

"The suspect has been shot and is being treated at NÄL [the regional hospital]. He is seriously injured and is being operated on", Niklas Claesson, hospital spokesman, said.

He dismissed earlier police reports the attacker had been killed.

Two boys, 11 and 15, and a male teacher are being treated for serious stab wounds at the hospital.