At least five people were killed Monday when a gunman opened fire in a nursing home in Croatia, according to local officials and state media.

State broadcaster HRT said an unidentified gunman entered a nursing home in Daruvar – some 130 kilometers (80 miles) east of Zagreb – and began shooting.

At least five were killed and several others wounded during the incident, HRT said.

Police said they were informed of the incident at 10:10 a.m. local time (8.10 a.m. GMT) and confirmed the suspect had entered the nursing home and used a firearm.

"The person linked to the perpetration of the crime is under police custody," police said in a statement.

The number of dead was later confirmed by Prime Minister Andrej Plenkovic, who called for a thorough investigation by relevant officials.

"We are appalled by the murder of five people at the home for elderly in Daruvar," Plenkovic said on social media.

The head of a regional emergency care facility, Nenad Mrzlecki, told local media that medical teams found four dead at the scene and four others wounded, who were immediately taken to local hospitals.

Mrzlecki did not provide information about the fifth victim.

"Our teams are still on the ground and the priority is to provide everyone with the necessary help, after that is done we will know the exact data on the number of victims," he said.

Croatian newspaper Jutarnji list described the alleged shooter as a "retired military police officer," who killed his mother along with other residents and staff.

Daruvar, a town of some 7,000, has long been a popular spa destination thanks to the area's thermal springs.

Shootings in the Balkan country are rare.

Last year, neighboring Serbia was rocked by back-to-back mass shootings, including a massacre at a school in the capital Belgrade in which 10 people were killed.