Sept. 16 (UPI) — Three people are dead in the aftermath of a shooting Tuesday that occurred near a middle school in a Chicago suburb.

Berwyn police described the incident in a press statement as a “domestic-related” that occurred outside of a Lincoln Middle School. Police have released few other details about the incident that comes less than a month after a gunman opened fire near a school in Minneapolis.

Officers in Berwyn responded to the shooting after hearing gunfire shortly after 4 p.m. CDT near Lincoln Middle School, where they saw a man firing a rifle into another vehicle, according to the press statement.

The man then opened fire on the officers, who took cover and did not return fire, police said. The nearby middle school went into “an immediate hard lockdown” to protect students and staff, police said.

Police did not identify the three people who died in what they called “an isolated incident” or other details about them. Police said that “all parties involved are accounted for” and the incident is under investigation.

Berwyn police Cmdr. Michael Fellows said during a news conference later that day that the gunman fatally shot himself after shooting two people in the other vehicle, according to the Chicago Sun-Times. Fellows called the incident “a very rare occasion.” He said police were still working to identify victims and that no students or staff were hurt “in any way.”

The school’s assistant principal said in a note that most students had already left for the day and those remaining in after-school programs were safe, reported CBS Chicago.