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ARVADA, Colo. — With temperatures dipping lower this week, police agencies across the state are reminding people not to puff.

It is illegal to leave vehicles running while unattended.

Police can issue citations for such situations and it could lead to vehicles being broken into.

According to law enforcement, vehicle thefts have increased nearly 60 percent in Colorado in the past four years.

The Denver Police Department has released three tips to warm up vehicles.

  • Always lock vehicles. According to police, up to 50 percent of personal property thefts happen because people leave their car doors unlocked with keys in the ignition.
  • Never leave anything valuable in a vehicle.
  • If you see something suspicious, report it to police.

In Denver, people who warm up their vehicles unattended can be ticketed.

The only major exception to the law is if vehicle owners have a remote starter.

In that case, they can be used, but vehicles can’t sit idle for more than five minutes.

Also, there’s an exception if it’s been less than 20 degrees for 24 straight hours or if the current temperature is below 10 degrees, according to Denver city law.