NORTH UTICA, Ill. (AP) — Three Chicago men killed in a explosion while fishing and making a fire unwittingly picked up an explosive rod that was left behind during a demolition project near Starved Rock State Park, according to lawsuits.

The families of the three men filed wrongful death lawsuits this week against companies that were hired by the state Transportation Department to demolish a bridge near the park in March.

Immer Rivera Tejada, 39, brother Rafael Rivera Tejada, 36, and their nephew Guillermo Rivera Tejada, 26, were fishing along the Illinois River in May, about 100 yards from the bridge demolition.

They had used a copper pipe to prop up a pan when making a fire, and heat caused it to explode, lawyers said.

“We always knew that Immer, Rafael, and Guillermo were innocent victims, and we knew the investigation would reveal that, which it did,” Immer’s wife, Maluc Cordoba-Arce, said in a statement.

Companies identified in the lawsuits declined to comment. Starved Rock is about 75 miles southwest of Chicago.

The men had seven children.