UPDATE: Woman, Child Killed In High-Speed Interstate 80 Crash Near Madison Avenue

SACRAMENTO (CBS13) — A woman and a child are dead after single-car accident that has closed westbound Interstate 80 on Thursday afternoon, after witnesses say the car was being chased.

A red Nissan Pathfinder collided with a tree just west of Madison Avenue around 2 p.m. on Thursday.

A woman and a child in a car seat were killed in the crash. An older child is currently in critical condition.

An off-duty officer spotted the Nissan Pathfinder moving at a high rate of speed and erratically on Interstate 80. The officer called it in on the radio inside the car and followed the car. The car had no lights or sirens, so it's not considered an official chase.