PALO ALTO -- A young woman has died after apparently jumping from an overpass into the No. 1 southbound lane of U.S. Highway 101 at San Antonio Avenue in Palo Alto Friday afternoon, according to California Highway Patrol Officer Ryan O'Day.

The woman was in her late teens or early 20s and was seen jumping from the overpass around 1:33 p.m., according to the CHP.

Witnesses told authorities they saw her "climbing over the protective fencing which is on the San Antonio Road overpass" right before jumping onto the highway, Palo Alto police Agent Wayne Benitez said.

The woman "was immediately struck by one car" after she jumped, O'Day said.

Benitez said a crew of paramedics who had been in the area immediately treated the woman, but that she died about 10 minutes after they began trying to resuscitate her.

Following the fatal collision another seven cars piled up behind the car that hit the woman, he said.

A Sig-alert was issued at 1:50 p.m., the CHP reported.

The southbound No. 1 fast lane and the No. 2 lane were closed until approximately 4 p.m.

Palo Alto police will be investigating the death because the woman jumped from an area under police jurisdiction, Benitez said.

Police aren't sure how the woman got to the area and will search for vehicles registered to her name and anything she might have left behind indicating why she jumped, according to Benitez.

The San Antonio Avenue overpass has seen suicides in the past, maybe one or two in the past seven years, he said.