Specially trained State Patrol troopers arrested four impaired drivers Wednesday morning on King County roads and highways. One driver was drunk and three others were impaired by drugs, according to the State Patrol.

The arrests:

-- At approximately 6:50 a.m., a repeat DUI offender pulled out of a parking lot and hit a school bus that was heading north on the Benson Highway near 208th Street in Kent. The bus was not carrying any children and the driver was not injured. The suspect, a 49-year-old Kent man, was treated for minor injuries and was arrested for suspicion of DUI.

-- At about 7:50 a.m., a driver was stopped for speeding through a congested 20 mph school zone on Highway 203 near Tolt Middle School in Carnation. The driver, a 26-year-old Issaquah man, was arrested for suspicion of driving under the influence of drugs, driving with a suspended license and possession of marijuana, the State Patrol.

Just before 10 a.m., several witnesses called 911 to report an erratic vehicle heading north on Highway 169 through Maple Valley. Troopers and King County sheriff's deputies stopped the vehicle and arrested the driver, a 24-year-old Kent man, for suspicion of driving under the influence of drugs and reckless driving. This was the suspect's second DUI arrest, the State Patrol says.

At about 11:20 a.m., a trooper working southbound Interstate 405 in Bothell stopped a vehicle for unsafe lane travel. The driver, a 23-year-old Everett man, was arrested for investigation of driving under the influence of drugs and possession of marijuana.

Last year, the national Drug Recognition Expert (DRE) program began teaching Advanced Roadside Impaired Driving Enforcement (ARIDE) classes to troopers and officers all over the country. ARIDE is a class designed to make law enforcement officers more proficient at detecting, apprehending, testing and prosecuting impaired drivers who are impaired by more than just alcohol.

All of the troopers involved in Wednesday's arrests are either DRE or ARIDE trained, the State Patrol says.