The fire in the nursing home, located in Andrasevac near Oroslavje, broke out in an auxiliary building of the home around 5 a.m.
Firefighters arrived at the scene quickly and the fire was put out around 6.30 a.m. They then started cooling the facility so that police could go inside and carry out an investigation.
PM Plenkovic expressed his deepest condolences to the victims' families, adding that one should wait for the competent services to complete their job.
Asked if the tragedy should result in stricter inspections of nursing homes, Plenkovic said: "Everyone will get involved - both county bodies and the competent ministry to see if inspections should be more frequent."
Krapina-Zagorje County head Zeljko Kolar and Oroslavje Mayor Emil Gredicak, too, arrived at the site.
Text: Hina