Swedish police say two people have been injured outside a Stockholm subway station after an unidentified explosive device detonated, apparently after someone picked it up from the ground to take a look at it.

Stockholm police told Swedish news agency TT the injured were a 60-year old man and a 45-year-old woman, with the man in serious condition. The explosion took place Sunday just outside the Varby Gard subway station in Huddinge, a residential district that is part of greater Stockholm.

Officials say the blast is not believed to be terror-related.

Rescue offical Lars-Ake Stevelind told Swedish broadcaster SVT that "someone has used some type of explosive material" for the object and that police is investigating it.