At least four towns in the Danbury area have seen a spike in car thefts and thefts from cars, most of which were left unlocked.

Over the past few weeks, police in Newtown, Redding, Bethel and Brookfield have urged residents to lock their cars, take their keys and not leave any valuables behind.

In Newtown, about a dozen thefts from cars have been reported since the beginning of the year. In addition, two cars were stolen from the same neighborhood within a two-week period this month, said Newtown Police Sgt. Aaron Bahamonde.

“That’s what we would (typically) have in a year’s time,” he said.

Both of those cars were stolen from Button Shop Road, which is off of South Main Street, and both were later found in Waterbury. The cars were left unlocked with the keys inside, police said.

Bahamonde believes the same group of thieves has been targeting area towns. He said similar cases have been reported in Middlebury, where 21 auto break-ins were reported in about a week this month, as well as in Waterbury and Brewster, N.Y.

“We’re definitely seeing a pattern,” Bahamonde said. “Our detective bureau is working closely with other area agencies to put all this information together. We’re all keeping each other in touch.”

In Brookfield, about 10 thefts from unlocked cars were reported, mostly on or near West Whisconier Road, on Friday or Saturday last week.

Officer Brian Flanagan, of Brookfield police, agreed that one group of thieves might be at work. He described such thefts as “a crime of opportunity.”

“They’re getting in, grabbing whatever they can, whatever is visible, and getting out,” Flanagan said. “To say it’s 10 seconds is probably a little long.”

Bethel police said earlier this month that a number of cars in the downtown area were stolen, broken into, or stolen and later returned. In several cases, the cars were left unlocked with the keys inside.

The latest thefts took place in Redding, where two unlocked cars parked on the same driveway on Route 58 were ransacked Monday night. Police said only a GPS device was stolen. Last month, however, a briefcase was taken from another unlocked car in the town.

Police Chief Douglas Fuchs said Redding normally gets about half a dozen such cases a year.

“The vast majority, almost all of them, are unlocked cars where valuables are in plain sight,” he said. “Why risk an alarm going off or someone hearing you break a window when you don’t have to?”

Bahamonde said the thieves likely are not carrying any burglary tools, and they should be identified and arrested soon.

“We’re not talking about professional car thieves,” he said. “They are taking advantage of people leaving unlocked vehicles to try to make a quick dollar.”

Some of the most common items stolen from cars in Newtown include laptops, GPS devices and even coins.

Meanwhile, police have stepped up patrols and urged residents to report any suspicious activity. Bahamonde also suggests residents install motion-sensor alarms or cameras in their driveways., 203-731-3411, @olivnelson