Two motorists who saw a driver run down and kill a 12-year-old boy on a bicycle Sunday were hailed as heroes for chasing him 10 miles at high speed, dodging his truck when he tried to run them off the freeway, police said.

"To call these citizens heroes is putting it mildly," said detective Bill Whittaker, who described the chase as "extremely dangerous and, really, unbelievable."The suspect was finally stopped by a police car and one of the witnesses when he drove into a dead-end street, Whittaker said.

Joel Espina, 23, of Los Angeles, was booked on suspicion of gross vehicular manslaughter while under the influence of alcohol.

The incident began about 12:30 p.m. when a pickup truck hit Carlos Grinaldo Jr. of Los Angeles on his bicycle. Grinaldo was taken to California Hospital, where he was pronounced dead.