COLUMBUS, Ohio — Two days after a gunman killed nine people outside a bar in Dayton, Gov. Mike DeWine of Ohio said Tuesday that he wanted to make it easier for the police to seize guns from people deemed dangerous.

“The momentum that has been created by this horrible, horrible tragedy I think is putting a spotlight on this,” Mr. DeWine said. “Now is a window of opportunity for us to change things.”

This is not Mr. DeWine’s first attempt to push the idea of a so-called red flag law, but this time he will be under enormous pressure to pass a bill through a Legislature controlled by his fellow Republicans. When Mr. DeWine spoke at a vigil near the shooting scene on Sunday night, grieving Dayton residents drowned out the governor’s voice with shouts of “Do something!”

[What are red flag gun laws, and which states have them?]

Some states that have experienced mass shootings have been able to pass legislation tightening gun laws. In Florida, where 17 people were killed last year at a high school in Parkland, the governor signed a version of a red flag law.