One woman and two children were killed, and one man was critically wounded, when a gunman shot them before killing himself in Suwanee, Ga., Wednesday. The 32-year-old gunman, Matthew Fields, 37-year-old Rebecca Manning and her sons, 8-year-old Jared Smith and 9-year-old Jacob Smith, as well as her father, 75-year-old Jerry Manning, all lived in the house where the crime took place, according to Fox News.

"We'd like to find a motive. There's no reason that any of us are ever going to understand to wipe [out] an entire family. We have absolutely no clue at this point what precipitated it," said Duane Piper, the Forsyth County sheriff, reported Fox News.

According to documents distributed by the sheriff's office, a 911 call was received at 6 a.m. Wednesday in which the caller stated that his wife was on the phone with her son, who said he had shot four people and was going to kill himself, reported the Associated Press. The man said they were heading towards the crime scene, which was 30 minutes away, because he believed that his wife was the only person who could talk to Fields. But the couple failed to make it on time, and he killed himself.

The gunman was known to have previous arrests for minor crimes.

Maj. Rick Doyle, from the Forsyth County sheriff's office, stated that they had visited the home the night before the killings on a domestic violence call. However, the people at the place were not cooperative, and officers did not find any sign of physical violence, so they had to depart the place, according to ABC News.