One man has died and a woman has been injured after an explosion at the Varby Gard subway station in Stockholm, Sweden. An object believed to be a hand grenade blew up after a 60-year-old man picked it up from the ground, leaving him fatally injured. A 45-year-old woman has also been taken to hospital with injuries, according to local reports.

"There was something on the ground that the man picked up, and then it exploded," Sven-Erik Olsson of the Stockholm police told the TT news agency.

The Aftonbladet newspaper reported that the blast was from was a hand grenade, though police have yet to confirm whether this is true.

The subway station and the nearby square have since been closed to the public as police and bomb squads investigate the scene.

The background to the incident was not immediately clear: “Someone has used explosives. We do not know more than that,” remarked fire department spokesman Lars-Ake Stevelind.

A report in 2017 showed that Sweden has come to rival crime-ridden Mexico for grenade attacks since the onset of the migrant crisis, with the problem growing so acute that a hand grenade amnesty has been proposed.