India, April 30 -- At least three people were killed and several others were injured in a shooting incident in the Swedish city of Uppsala on Tuesday, media reports said.

In a statement, the police said they had received calls from people who heard sounds of gunshots in the city centre, news agency Reuters reported.

The police have cordoned off a large area, and a murder investigation is underway.

The incident happened on the eve of the Walpurgis spring festival, which brings a large number of people onto the streets of Uppsala, a city located north of the capital Stockholm.

A "major effort" is currently underway, with a police helicopter joining in the search for the shooter, police spokesman Magnus Jansson Klarin told TV4.

Train se...