A man was killed and a woman injured in an explosion on Sunday outside a metro station in Stockholm, Sweden, police said.
A woman in her mid 40s was also taken to hospital, but her injuries were not described, local media reports.
The blast, at the Varby Gard station in the municipality of Huddinge, which is about 11 kilometers south of Stockholm, took place when someone picked up an object, which then exploded, Swedish Television reported on Sunday.
"These two people cycled past the object and stopped to see what was on the ground".
Police at the scene of the incident.
Police checked in and around the subway station after the blast to make sure there were no other explosive devices.
"We're suspecting that it's a hand grenade of some sort", Lars Alvarsjo, chief of Stockholm's southern police district, told the Swedish national broadcaster SVT.
Mr Alvarsjo said Swedish police have "unfortunately" noticed a rise in the use of hand grenades by criminal groups. "I don't dare imagine what would have happened if one or several children had found the hand grenade".