A man rammed his car into a woman's car on I-270 yesterday morning, assaulted her, bit off her right eyebrow and fled when a passing motorist intervened. Police later confronted a man they believe to be the attacker on Georgia Avenue in Silver Spring, where he attempted suicide.

Jonnie A. Royes, 23, of 7620 Maple Ave., Takoma Park, was charged with three counts of assault (with intent to murder, rape and maim) against the 31-year-old Silver Spring woman, police said.

When the woman pulled to the shoulder of I-270 at Old Georgetown Road in Bethesda about 8 a.m. to investigate the damage to her car from the ramming, the man allegedly pulled her from the car, pushed her over the guardrail and dragged her down an embankment to some bushes. There, police said, she suffered hand cuts from a knife and was bitten on the arm and face.

Retired Marine Col. Bruce Franklin Ogden, 52, of Crofton, Md., interrupted the assault, according to police. "I tried to flag down cars . . . for about 10 seconds," Ogden said yesterday. He said he then grabbed her as she scrambled up the embankment and took her to State Police barracks. She underwent surgery at Shady Grove Adventist Hospital and was released.

A short time after the assault, Montgomery County police reported, officers saw a car on the shoulder of Georgia Avenue at the Beltway in Silver Spring. Upon investigation they saw a man, later identified as Royes, taking his clothes off and thrusting a knife into his throat. Royes was treated at Holy Cross Hospital and released to police.