Senior Sergeant Gary Hughes said the duo was able to steal a range of tools, cash and personal items from the vehicles, which were located in residential areas in Swan Hill.

Sen Sgt Hughes said the most alarming thing about the alleged offences was the ease in which the thieves were able to take the items because all the cars had been left unlocked.

"People are pretty mindful when they park within the CBD, but when they get home and park in the street or driveway they're very remiss about locking their vehicles," he said yesterday.

"We need to get a message out to start locking our cars because in just one night, they managed to find 20 vehicles around the Swan Hill area."

Sen Sgt Hughes said assistance from an alert community member led to the arrests.

The youths are charged with theft and criminal damage.

One of the alleged offenders is a 13-year-old Swan Hill youth, who has been bailed under strict conditions.

The other person accused of the thefts is a 15-year-old Swan Hill youth, who was also released on bail following a hearing at the Swan Hill Magistrates' Court yesterday afternoon.