The thieves strike mostly in the predawn hours, silently slipping into cars on residential streets in towns throughout Essex County.

They're searching for keys, but they'll take whatever they find, loose change, glasses, electronics, and even owner's manuals.

It's not really a matter of make or model. But the cars do share something in common:

Nearly all are left unlocked.

"This apparently is the new crime of opportunity," said Lt. Peter Eakley, the public information officer for Millburn Police Department.

Investigators have been tracking the rising trend, which has spared few communities. With the number of car break-ins rising steadily, the Essex County Prosecutor's Office is keeping track of the numbers. For the past month, the office has logged in 141 vehicle burglaries in 15 towns in West Essex (Aug. 15-Sept. 15), but is not actively involved in the investigations, said spokeswoman Katherine Carter.

Millburn, Montclair and West Orange have suffered the greatest number of burglaries, officials with the prosecutor's office said.

In a one-month period alone (from Aug. 15 - Sept. 15), there were 26 vehicle break-ins in West Orange, 28 in Millburn and 24 in Montclair.

West Orange Police Chief James Abbott said there's "no discernible pattern" in the vehicle burglarizations except that many of them occur over the weekends. He said the department has met with neighboring towns to see how they can work together to address the issue.

According to the prosecutor's office, 59 percent of the thefts to motor vehicles are happening in people's driveways.

Stolen cars have seen a huge spike as well: The number in Livingston – 23 from January through this week – is more than the past three years combined, said Detective Sgt. Anthony Dippold. In Millburn since January there have been 165 break-ins and 23 car thefts. Montclair has been hit with 108 break-ins and 76 car thefts.

"Without a doubt this is an increase, and we are working on a regional basis to combat this situation," Eakley said.

Local police departments are grappling with ways to stop the crimes and, at the same time, educate residents on ways to protect themselves.

For example, earlier this year, Belleville created a task force specifically to deal with car break-ins and took prints at the scene, something that is not always done because of the expense.

In Montclair, where stolen cars have climbed 228 percent this year over last, Deputy Chief Todd Conforti said, "We would ask that residents assist in preventing these types of crimes by regularly locking their doors and windows to their vehicles and to quickly report any suspicious activities that they observe."

In Livingston, the rise in crime has renewed interest in Neighborhood Watch. Komal Panjabi, a Livingston resident, met with local police to begin one in her small 30-home community of Hillside Heights.

"My neighbor's car was stolen from her driveway right across the street, which made me nervous and there have been other incidents as well," Panjabi said. "We need to be more vigilant."

Police suspect several groups are operating in the towns. They look for unlocked cars and ransack glove compartments, mostly taking money, sunglasses, and portable GPS units.

They'll take the car if you let them. Valet keys and electronic key fobs left in the car offer an easy get-away.

While this piece of advice should be a no-brainer, 65 percent of car break-ins are from unlocked cars, said Abbott.

Simply locking the doors will deter those looking for an easy target. Electronic key fobs are also blamed, as newer models with start buttons can be activated even if the key fob in a home is placed close enough to the vehicle.

"It's all about key maintenance, key control," Dippold said, "knowing where your keys are at all times."

Karen Yi, Laura Griffin, Shelley Emling and Paul Milo contributed reporting.