WASHINGTON (CBS SF) — Calling it one of those near misses of her life, Sen. Dianne Feinstein said her daughter had planned to attend the concert where 58 people were killed and more than 500 injured by a lone gunman but changed her plans at the last minute.

Feinstein made the revelation at a news conference to announce legislation ban the kind of converter device that gunman Stephen Paddock used to upgrade his semi-automatic weapons to deadly military quality automatic weapons.

READ MORE: Update: One Killed, Two Injured When Truck Crashes Into Diners at San Jose Sports Bar

The California senator told reporters her only daughter — Katherine Feinstein Mariano — had planned to attend the concert with friends.

“When you see a country music festival, when you see 18 year olds in boots and hats — my own daughter was going to go,” she said. “I have an email from her. She was going to go with neighbors. For one reason or another, both families decided that they wouldn’t. They were going to stay at that hotel. That’s how close it came to me.”

“I just thank God. It’s one of those misses in life. It could happen to anyone of us.”

Feinstein also reached back to San Francisco’s darkest day, it calling for passage of her bill. Speaking to reporters while flanked by Sen. Bernie Sanders and Sen. Richard Blumenthal, Feinstein said she knew the damage a gun could do.

“I never thought in this country we’d see something like this (the mass killing in Las Vegas),” she said. “I have found as you all know someone shot to death who was a colleague of mine and the mayor was shot to death. I know what guns can do.”

LAS VEGAS MASSACRE: Continuing Coverage

Feinstein was the president of the San Francisco Board of Supervisors in November of 1978 when former Supervisor Dan White assassinated Supervisor Harvey Milk and Mayor George Moscone. She found Milk’s body and told the media what had happened. Feinstein would be named Moscone’s successor.

READ MORE: UPDATE: Authorities Release New Details About Milpitas Couple Who Ran Network of South Bay Brothels

The senator said the killing of 59 people and the injuring of more than 500 had taken the issue of gun control “into war.”

Paddock unleashed hundreds of rounds of gunfire onto the crowd of concertgoers with 12 weapons that had a device called a “bump stock” attached that allowed the semiautomatic rifles to mimic fully automatic gunfire.

The bump stock modifications have attracted scrutiny from authorities and lawmakers in recent years.

“Individuals are able to purchase bump fire stocks for less than $200 and easily convert a semi-automatic weapon into a firearm that can shoot between 400 and 800 rounds per minute and inflict absolute carnage,” said Feinstein on Tuesday.

Her legislation — the “Automatic Gunfire Protection Act” — will likely be opposed by other lawmakers. While she hasn’t had time to reach out to Republican senators, Feinstein said she had 26 Democrats on board.

READ THE BILL: Automatic Gunfire Protection Act”

“Are these things (pointing to a photo of a “bump stock” device) something we want sold over the internet,” she said. “So (someone) could easily change a weapon bought legally into a weapon that would be totally illegal and with good reason…Just to kill large numbers of people.”

When it comes to opposition to her bill, Feinstein issued a plea “to Mr. and Mrs. America.”

MORE NEWS: 'In the Heights' Delights at First Pride Movie Night at Oracle Park

“Mr. and Mrs. America you have to stand up,” she said. “You have to say — enough is enough. You have to say there is no reason to make a semi-automatic assault weapon into a fully automatic battlefield weapon.”