Three people have been saved from an alleged kidnapping in Northland and two men have been arrested, thanks to a well-placed roadside breath-testing checkpoint.

An investigation is now under way to untangle the details.

Police officers were running a checkpoint on Riverside Drive in Whangārei on Saturday night when, about 10.50pm, a man jumped out of a car and raised concerning claims.

Based on the information, police quickly arrested the driver, a 31-year-old patched member of the Crips gang, the only other occupant of the car.

Police spoke with the driver and his passenger before turning their focus to a home on Eureka Pl, Parahaki, where two more people were allegedly being held against their will.