An armed Norwegian man stole an ambulance and drove it along a pavement in Oslo, injuring two infants, as police tried to stop him by shooting at the tyres and ramming the vehicle.

The 32-year-old man was injured and arrested on suspicion of attempted murder, authorities said.

Inside the stolen ambulance, police found a submachine gun, a shotgun and what they said were "large amounts" of narcotics.

An image of the man being pinned to the ground by police has emerged since the incident and arrest took place.

The ambulance crashed into a gate. Credit: AP

"It is too early to say whether this is terror-related, but we are investigating broadly and fully," police said in a statement.

Investigator Grete Lier Mettid said the suspect was known to have ties to far-right groups. Police did not identify him by name.

"It is, however, too early to say anything about the motive," Lier Mettid told a news conference in the Norwegian capital.

Oslo police tweet gives bare details of the incident. Credit: Twitter

Johan Fredriksen, a senior police officer, said the ambulance ran into a pushchair carrying two seven-month-old twins, although they are not believed to have been seriously injured.

An elderly couple who dived under a parked car to avoid the ambulance escaped injury.

Police shot at the tyres to stop the ambulance and did not target the man, Fredriksen said. The vehicle stopped after being rammed by police.

Police in Oslo, Norway have shot and wounded a man who drove at people. Credit: Stian Lysberg Solum/NTB scanpix via AP

A video posted by several Norwegian media showed how police pulled the man out of the ambulance through the side window because the front door had been damaged when it collided with obstacles, including a road sign.

The yellow-and-blue ambulance was stolen after authorities responded to a traffic accident on an Oslo roundabout in which a car had turned over. The man left the scene on foot and pointed a weapon at police before stealing the ambulance.

The ambulance appears to have bullet holes in the driver's side door. Credit: Stian Lysberg Solum/NTB scanpix via AP

A 25-year-old woman who was a passenger in the overturned car was later arrested. The man and woman are known to police, Lier Mettid told reporters.

Anders Bayer, a spokesman for Oslo University Hospital, confirmed to Norwegian news agency NTB that the ambulance was stolen by an armed person. Three employees in the vehicle when it was stolen were unharmed, Bayer added.

The Aftenposten newspaper published a photo showing a man wearing green trousers lying next to the vehicle surrounded by police officers. Another photo showed a handcuffed man, flanked by police, walking toward an ambulance stretcher.

A witness told the newspaper the ambulance was driving at high speed followed by a police car in pursuit.

"I heard several shots," Omar Khatujev told Aftenposten.