ST. LOUIS — In what’s been a violent year in St. Louis, a common theme has emerged: The gun used in any given crime was probably stolen.

The city is on pace for around 200 homicides in 2015, the most in 20 years.

Meanwhile, reports of gun thefts are up nearly 70 percent, police chief Sam Dotson said. But it’s not homes, gun stores or pawn shops that thieves are targeting, Dotson said: It’s cars and trucks.

More than 170,000 Missouri residents hold concealed-carry permits and many bring guns when they venture to high-crime areas like St. Louis.

Numerous city-dwellers, too, own firearms. But once they arrive at their destination, they often have to leave their guns behind.

“When they go to a baseball game or an event at the convention center … they can’t take their weapons in with them and they leave them in cars,” Dotson said.

“Criminals know there are guns in cars and they break into cars.”

In Jacksonville, Florida, gun thefts from cars are so common that police have launched a social media campaign to persuade people to keep their weapons at home.

“It’s a big issue,” Jacksonville Sheriff’s Office spokeswoman Melissa Bujeda said.

“Criminals are just going car-hopping, looking for unlocked doors and people who are leaving their guns in their cars.”

“I think the message is that lawful people who want to have a gun, be smart about it,” Dotson said. “Don’t leave it unsecured in cars.”