Petaluma Police arrested 20 people Friday night in a drunk driving sting.
Checkpoints were staged at Lakeville and Wilson streets between 6 p.m. and 9 p.m. and at East Washington and Lakeville streets between 10 p.m. and 2:30 a.m.
A total of 1,680 vehicles passed through the two checkpoints and 1,668 were screened for signs of DUI.
Of the 86 drivers who were put through either DUI evaluation or drivers license checks, 20 were arrested.
There were 10 DUI arrests, one arrest for violating DUI probation for driving with alcohol in their system, three for driving on a suspended license and six for driving without a license.
A total of 19 vehicles were towed and 11 were impounded for 30 days from unlicensed or suspended drivers.