JACKSONVILLE, Fla. — Family members of three Black people fatally shot at a Dollar General store in north Florida by a racist gunman have sued the store’s landlord, operator and security contractor for negligence, claiming lax security led to their loved ones’ deaths.

The 21-year-old gunman had attempted to enter another store and the campus of a historically Black college, but he was stopped by the presence of security guards at both places. The probes by Ryan Palmeter took place in a predominantly Black neighborhood in Jacksonville last August, ending in the fatal assault at the Dollar General.

The lawsuit was filed Monday on behalf of the families of Angela Carr, Jerrald Gallion and A.J. Laguerre.

“While Palmeter was deterred from harming the public at his two preceding stops, at this Dollar General, there was nothing in place to again deter Palmeter from attacking and killing innocent persons,” the families’ lawsuit said.

Better security measures should have been in place by the store operator and landlord before the shooting last August since the area around the store had seen a rash of shootings, assaults, burglaries, robberies and drug dealing, the lawsuit said.

The lawsuit was filed in state court in Jacksonville. Palmeter killed himself at the scene of the attack, leaving behind racist writings and a suicide note.

The families of the victims also named Palmeter’s estate and his parents as defendants in the lawsuit.

Investigators have said Palmeter made clear in his writings that he hated Black people. During the attack, he texted his father and told him to break into his room and check his computer. There, the father found the note and the writings. The family notified authorities, but by then the shooting had already begun, detectives said.

Palmeter had been involved in a 2016 domestic violence incident that did not lead to an arrest and was involuntarily committed for a 72-hour mental health examination the following year. Palmeter used two guns in the shooting, a Glock handgun and an AR-15-style rifle, according to authorities.

An email seeking comment from Dollar General’s corporate offices was not immediately returned.