A man shot dead 13 members of his family and neighbours, including a two-year-old child, as he went on a rampage in a village outside the Serbian capital Belgrade, police said on Tuesday.
In the bloodiest murder spree in Serbia in two decades, the man shot most of his victims in the head as they were sleeping before he shot and wounded himself, police said.
The motive for the pre-dawn Tuesday attack was not immediately clear.
"Twelve people were killed on the spot while the thirteenth died in a hospital emergency room," head of Serbian police Milorad Veljovic told journalists.
"Doctors are trying the save lives of three injured, including the perpetrator of this monstrous murder," he said.
It was the killing spree with the most victims during the past two decades in Serbia, a police source told AFP.
The national RTS television identified the attacker as sexagenarian Ljubisa Bogdanovic, who it said killed six men, six woman and a baby. Police said the 13th victim was a two-year-old child.
The victims were killed around 0300 GMT in five different houses in the village of Velika Ivanca, some 50 kilometres (31 miles) south of Belgrade, inhabited mostly by the gunman's relatives, Veljovic said.
"There are a total of five houses, belonging to his family and his neighbours. We still dont' know the motive," he said.
All the victims were sleeping when they were attacked and were practically all shot in the head, he added.
The killer is believed to have first killed his 42-year-old son, then his mother, and wounded his wife before continuing his killing spree.
Police later found him in the yard of one of the houses where he tried to commit suicide. The gunman was hospitalised with head injuries and doctors were fighting to save his life, Veljovic said.
According to police, the killer had a firearms licence.
Investigators were checking the gunman's past as so far nothing from his current life hinted why he committed such a crime, a police source told AFP.