Two people were killed and 14 wounded on Saturday in a shooting at a nightclub and in nearby streets in Norway's capital Oslo, police said, Reuters reported.

A suspect believed to be the sole perpetrator was apprehended, police told reporters.

The crime scene extended from the London Pub via a neighboring club and onwards to a nearby street where the suspect was apprehended a few minutes after the shooting began in the early hours of Saturday, police spokesman Tore Barstad told newspaper Aftenposten.

The London Pub is a popular gay bar and nightclub in the centre of Oslo.

"I saw a man arrive with a bag, he picked up a gun and started to shoot," journalist Olav Roenneberg of public broadcaster NRK reported.

It was not immediately clear what the motive for the attack was.

Two people were confirmed dead and some 14 people were taken to hospital, several with severe injuries, police said.

Oslo's university hospital said it had gone on red alert following the shooting.