A man who has delivered more than 26,000 white crosses to sites around the US, largely to remember victims of gun violence, has now found himself doing the same in his hometown: Aurora, Illinois, where five people were killed and six injured in a workplace shooting on Friday.

“I just didn’t see it coming,” said Greg Zanis, who made crosses for the victims of an employee about to lose his job who opened fire inside the Henry Pratt Company warehouse.

Police identified those killed as Clayton Parks of Elgin a human resources manager; Josh Pinkard of Oswego, a plant manager; Russell Beyer of Yorkville, a mold operator; Vicente Juarez of Oswego, a stock room attendant and forklift operator; and Trevor Wehner, a new intern.

One employee and five police officers were wounded. All were expected to survive.

Zanis has set up crosses after mass shootings in Las Vegas, Columbine, Sandy Hook and Orlando. Before Saturday, his running total was 26,274 over 22 years. The number is now 26,279.

Last year, Zanis said, he made 5,000 crosses. Recently he had been working on a batch of crosses for victims of Chicago gun violence that he was to deliver to a Sunday vigil.

On “the best lumber I can find”, Zanis puts two coats of white paint, a large red heart, the victim’s name and a serial number.

Greg Zanis works on one of the 58 white crosses he set up for the victims of the 2017 mass shooting in Las Vegas. Photograph: Chris Wattie/Reuters

He said he heard squad cars on Friday afternoon because he lives near the police station in Aurora. Shortly afterwards, he heard about the shooting at the warehouse.

He started making crosses when he heard people had died. He placed five outside the warehouse on Saturday.

Zanis usually places the crosses and leaves. But he said he would attend all the vigils and funerals for the Aurora victims.

“I feel like I am carrying the weight of the whole city on my shoulders,” he said.