A tram came off the tracks in a bustling commercial neighborhood of Olso on Tuesday, smashing into a phone and computer shop, Norwegian police said.

While the store suffered extensive damage, no deaths were reported. The tram driver and three other people sustained only minor injuries.

What we know about the accident

The tram was said to have jumped the rails, continuing straight ahead when it should have curved left.

Its front section crashed deep into an electronics retailer selling Apple products. At least one pedestrian had to leap out of the way as the wayward tram made its unexpected detour.

"Three people on board the tram were injured and another person outside" also sustained injuries, the head of police operations at the scene, Anders Ronning, told the AFP news agency.

None of the injuries are reported to be serious, according to Ronning. 

Police initially said at least 20 people were on board the tram, although some passengers had already left when emergency crews arrived.

The tram smashed deep into the store, surrounded by glass and debris, and the damaged building, which also houses offices, was evacuated.

Officials said the tram would not be removed until experts determine the stability of the building's load-bearing walls.

Excess speed a possible cause

One witness told the daily newspaper Verdens Gang that the scene was surreal.

"If everyone came out of this unharmed it means there's someone watching over us, because it was a powerful crash, to put it mildly,"  Andre Norheim told the newspaper.

Police said they were waiting for Norwegian Safety Investigation Authority to arrive to help determine the cause.

The driver was formally declared a suspect by police, amid speculation that the accident was caused by excessive speed.

The city's tram system carries about 50 million passengers a year, according to Oslo's trams and subway trains' operator Sporveien.

rc/dj (AFP, AP, dpa, Reuters)