BELGRADE, Serbia (AP) -- Serbia held a national day of mourning Wednesday as police searched for possible motives in the Balkan nation's worst peacetime shooting massacre, which left 13 villagers dead and triggered demands for tighter gun-control laws.
Police say a 60-year-old veteran went on a pre-dawn, house-to-house rampage Tuesday in a village near Belgrade, including killing his mother, his son and a two-year-old cousin before shooting himself and his wife. The two are in critical condition in a Belgrade hospital.
Police say they have no clue as to why the suspect, identified as Ljubisa Bogdanovic, went on the shooting spree. They said he had no criminal record or history of mental illness. He did fight in the bloody Balkan wars in the 1990s and lost his job a year ago at a wood processing factory.
Police chief Milorad Veljovic said he hoped the suspect's wife could provide the motive. Davorka Bogdanovic, 60, who has severe neck and head gunshot wounds, was still able to communicate with the hospital staff.
Belgrade media quoted her as telling doctors that "there were no hints that he would do this."
"He had a bad temper, but I didn't dream of this," the Vecernje Novosti newspaper quoted her as saying.
The suspect's older brother Radmilo told The Associated Press that his brother had changed after serving in the army during the Serb-led offensive against the eastern Croatian town of Vukovar in 1992 -- the worst bloodshed during Croatia's 1991-95 war for independence.
"The war had burdened him," Radmilo, 62, said Tuesday. "He used to tell me: God forbid you live through what I went through ... Something must have clicked in his head for him to do this."
Residents of the village of Velika Ivanca, some 50 kilometers (30 miles) southeast of Belgrade, said Bogdanovic first killed his son and his mother before leaving his house and then went house to house, shooting his neighbors. They expressed deep shock, describing the suspect as a quiet and helpful man.
"It is possible that some changes had happened gradually to him, and that's why no one noticed," psychologist Aleksandar Dimitrijevic said. "I think something awful happened to him and that this mystery will never be solved."
Serbian officials said the killings showed that the government must pay more attention to gun control, medical screening for war veterans and other social problems facing the Balkan nation, which is still reeling from the 1990s wars.
Although such mass shootings are relatively rare in Serbia, weapons are readily available, mostly from the latest wars. Media reports said the suspect had a license for the handgun he used.
Veljovic, the police chief, said the government is working on a new gun control law.
"The law calls for regular medical checkups for those possessing weapons," he said.
Serbia has about three million weapons owned by civilians, according to the Small Arms Survey, a non-governmental organization from Switzerland. It says Serbia has the fifth-highest number of weapons per capita in the world, with some 38 firearms for every 100 people.
The United States has the highest ratio -- 88 weapons per 100 people -- while England and Wales were low down on the list with 6.2 weapons per 100 people.
Associated Press writers Jovana Gec in Belgrade and Aida Cerkez in Sarajevo contributed.
Copyright 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.