Canadian police have charged a man over the deaths of two police officers and two civilians in a shooting that struck a nerve in a country that has been hit in recent months by several incidents of mass violence.

Police in the eastern city of Fredericton, New Brunswick, said in a statement Saturday that Matthew Vincent Raymond, 48, was arrested and charged with four counts of first-degree murder.

Horizon Health, which delivers care for New Brunswick’s Department of Health, said that Raymond was the only person being treated for injuries related to the shooting.

He is due to appear in court August 27.

The victims have been identified as Pc Robb Costello, 45, Pc Sara Burns, 43, Donnie Robichaud, 42, and Bobbie-Lee Wright, 32.

Robichaud and Wright were in a relationship, according to Facebook and Robichaud’s cousin, Sean Callahan, who said they had just got together at the beginning of August.

No motive has been disclosed.

Fredericton’s deputy police chief Martin Gaudet said the two officers were responding to calls of shots fired at an apartment complex.

He said they arrived and saw two dead civilians before being shot and killed themselves.

The shooting comes as Canada wrestles with a string of violent acts, including an incident in Toronto last month where a man with a handgun opened fire in a crowded part of the city, killing two people and wounding 13 before he died in the confrontation.

In April, a man who linked himself to a misogynistic online community used a van to run down pedestrians in a busy part of Toronto, killing 10 people and injuring 14.

Authorities are also still pursuing leads in an ongoing investigation of a serial killer who has been charged with killing eight men in the city in recent years.

In 2014, a shooting in Moncton, New Brunswick left three Royal Canadian Mounted Police officers dead and two wounded.