Police say the boys, who have not been identified, were trying to cross NE 4th Street in the 3700 block just before 5 p.m. when they were hit.
They were not in a crosswalk and police say traffic on the road was very heavy.
"One car going eastbound saw them and was able to stop. The other driver going eastbound was unable to see them because his vision was blocked. He hit the brakes, but the two juveniles were struck," said Clark Wilcox with the Renton Police Department.
One of the teens was seriously injured and was rushed to Harborview Medical Center to be treated for head and body injuries. The second boy was taken to Overlake Hospital to be treated for injures to his body, according to police.
The department's traffic unit is investigating the crash, but police say the driver wasn't impaired and wasn't speeding when he hit the teens.
"Naturally, he's very shook up. This was a very traumatic scene for him," Wilcox said.