Route 78 fatalities
Sandra Ortiz was arrested on suspicion of DUI and vehicular manslaughter. Photo by Gilberto Gonzalez/SoCal News Outlet

A woman was behind bars Monday on suspicion of DUI and vehicular manslaughter in connection with a Vista freeway accident that killed her two children over the weekend.

The events that led to the double fatality on the eastbound side of state Route 78 began shortly after 6 p.m. Sunday, when Sandra Ortiz, 33, pulled over for unknown reasons near Mar Vista Drive, according to the California Highway Patrol.

After the vehicle came to a stop, Ortiz’s children, ages 10 and 16, got out and were hit by an oncoming car, the CHP reported. The victims, whose names were not immediately available, died at the scene.

It remained unclear Monday why Ortiz stopped on the side of the freeway, though it may have been because a piece of luggage she had tied to the roof of her vehicle had come loose, according to news accounts.

Ortiz was being held at Las Colinas women’s jail in Santee on $500,000 bail pending arraignment, scheduled for Thursday afternoon.

City News Service contributed to this article.