According to authorities, a former Marine sharpshooter who served in Afghanistan fatally shot four people, including an infant, on Sunday morning in two houses near Lakeland, Fla., and exchanged gunfire with deputies before being arrested.

The motive for the rampage was not immediately apparent to investigators.

Grady Judd, the sheriff of Polk County, Fla., told reporters that at least one bullet was fired during the two gunfights in which The suspect shot dozens, if not hundreds of rounds at the gunman and an 11-year-old girl.

Authorities said three of the people killed were found inside one home – a 40-year-old man, a 33-year-old woman, and a 3-month-old boy the woman was holding. Another victim was found dead on the property, the infant’s 62-year-old grandmother.