Residents were allowed to turn in weapons without fear of criminal prosecution and the elderly man showed up with the grenades, the Swedish news agency TT/The Local.se reported Friday.
"The reaction was swift. We evacuated the whole police station and a nearby building was cordoned off," police spokesman Peter Sarman said. "It's only specially trained police officers who can determine whether such grenades are armed or not. We were forced to play it safe."
Sarman said the grenades were determined to be inactive.
A police department Facebook post said anyone else seeking to turn over explosives should not transport them to the stations themselves. Police recommended calling in bomb technicians to get rid of any explosives.
"Grenades can detonate during transportation," the posting said.