High school students grieved at a northwest Washington candlelight vigil after an SUV earlier jumped a curb and plowed into a group of teens out for a gym class walk, killing two boys and seriously injuring two others.

About 30 students from Windward High School in Ferndale, north of Bellingham, were out walking with a teacher Wednesday afternoon when the vehicle left the road and hit the four teens, who were on a sidewalk, Trooper Mark Francis said.

The 34-year-old driver, identified as William Klein of Bellingham, was arrested for investigation of vehicular homicide and vehicular assault, Francis said. The man had his 3-year-old son with him; neither was injured.

The driver initially said he fell asleep at the wheel but later told a drug recognition expert he had used drugs, Francis said.

"The expert also observed signs of impairment," the trooper said. He would not discuss what drug or drugs were mentioned.

Dozens of students gathered Wednesday night for a vigil at the nearby Windward campus.

Some classmates walking behind those who were struck watched the crash happen, Francis said.

"Just heard just the worst yell - just, 'No! No! No!'" Shelley Hardt, who was working nearby, told KOMO-TV. "You knew that something really, really bad had happened. So I ran outside as fast as I could."

Lynnette Delamare and her husband live nearby and had watched the teens walk by. Then they heard three or four loud crashes from the street.

"We went running out and there was just bodies everywhere, so we didn't know which one to go to," she told KING-TV. "Finally more people started coming and we got blankets and we knew right away .... two of them were not moving."

Shane Ormiston, 18, and Gabriel Anderson, 15, both of Ferndale, were killed, the State Patrol said.

Two 17-year-olds — Michael Brewster of Custer and Kole Randall of Ferndale — were injured. Both suffered severe leg fractures, the Bellingham Herald reported.

Brewster was transferred to Harborview Medical Center in Seattle, where a nursing supervisor said he was in satisfactory condition late Wednesday. The other boy was reported in serious condition at St. Joseph Medical Center in Bellingham.

"There are simply no words to soothe the pain of this loss," Ferndale Mayor Gary Jensen said in a statement. "Ferndale is hurting and we mourn together, as a community."