Two people were arrested Friday night at sobriety checkpoints in Cloverdale and Healdsburg — the opening act of an aggressive, weekend-long campaign against drunken or impaired drivers.

The first checkpoint screened southbound drivers on South Cloverdale Boulevard at Franklin Street. Later in the evening, the checkpoint was relocated to screen southbound drivers on Healdsburg Avenue just south of Mill Street.

Officials said that of the 322 vehicles stopped, 28 drivers were given field sobriety tests. Two were arrested on suspicion of driving under the influence of alcohol. One driver was arrested on an outstanding warrant.

Four drivers were cited for driving on suspended licenses, and three were cited for driving without licenses. No vehicles were impounded.

The checkpoints were part of a countywide law enforcement effort aimed at catching and discouraging driving while under the influence of drugs or alcohol.

Five checkpoints are planned for Santa Rosa during the remainder of the holiday weekend.