A guitarist's viral tweet explains why he changed his mind about gun control.

"I've been a proponent of the 2nd amendment my entire life. Until the events of last night," began a tweet from Josh Abbott Band guitarist Caleb Keeter.

Just hours before, Keeter and his bandmates hid as bullets flew through the air at the Route 91 Harvest Festival in Las Vegas, killing more than 50 and injuring upward of 500 people. The band performed earlier in the day on Sunday and were watching the other acts when a gunman opened fire on the unsuspecting crowd.

"I cannot express how wrong I was," Keeter tweeted. "We actually have members of our crew with [Concealed Handgun Licenses], and legal firearms on the bus. They were useless."

Keeter's tweet is a sober reflection on how living through a mass shooting changed his mind in such a huge way.

"We couldn't touch [the guns] for fear police might think that we were part of the massacre and shoot us. A small group (or one man) laid waste to a city with dedicated, fearless police officers desperately trying to help, because of access to an insane amount of fire power. Enough is enough."

As Keeter alluded to, the "good guy with a gun" theory might sound great to lawful, trained gun owners; it's just not necessarily backed up by a lot of data. He notes that one concern was the chance that officers might misidentify them as shooters, which is something that sometimes happens, according to a 2014 report by the FBI. Additionally, the Las Vegas shooter reportedly was firing from a hotel room 32 floors up. Firing back up at him with handguns from the ground would only put others in the hotel at risk.

Photo by David Becker/Getty Images.

Gun violence has gotten "completely and totally out of hand," Keeter wrote.

"Writing my parents and the love of my life a goodbye last night and a living will because I felt like I wasn't going to live through the night was enough for me to realize that this is completely and totally out of hand. These rounds were powerful enough that my crew guys just standing in a close proximity of a victim shot by this fucking coward received shrapnel wounds. We need gun control RIGHT. NOW."

"My biggest regret is that I stubbornly didn't realize it until my brothers on the road and myself were threatened by it. We are unbelievably fortunate to not be among the number of victims killed or seriously wounded by this maniac."

There aren't any positives in a horrific event like this — no silver lining. Still, there's hope that we can learn from tragedy.

Caleb Keeter had a revelation Sunday night. That's worth something.

In response to Keeter's change of heart, people have been critical of the fact that previous mass shootings like the one at Sandy Hook or the Pulse nightclub weren't enough to open his eyes, and others have been welcoming of his presence in the fight for common sense gun control. "It's frustrating that some don't call the fire dept. until the blaze is at their own front door," one person tweeted. "But we need more ppl on our side. Welcome."

For his part, Keeter has acknowledged that he could have — and probably should have — changed his mind on the issue a while ago.

That any of us can see the absolute carnage gun violence creates in this country and not acknowledge that there needs to be some restrictions on what the average citizen should be allowed to carry speaks to the power of lobbying and messaging of groups like the NRA. Hopefully, with the help of Keeter, some of that damage can be prevented in the future.