Honolulu police will be manning impaired driver checkpoints at unannounced times and locations during the July Fourth holiday weekend, and ending on Monday.

As of June 30, 24 people have been killed in traffic crashes on O'ahu, police said in a news release. Alcohol and speed were factors in at least four of those crashes. Thirty-six people were killed in traffic crashes at the same time last year.

HPD and the state Department of Transportation will continue its partnership in the federal "52/12" sobriety checkpoint program. Through September 2008, police will conduct at least one sobriety checkpoint every week, police said.