OAKLAND -- A woman trying to cross Interstate 580 early Thursday morning was killed when she was struck by a pickup truck, police said.

The woman was identified as Adriana Castellanos-Remirez, 42, of Oakland, a spokeswoman for the Alameda County coroner's office said.

It is not known why Castellanos-Remirez was on the freeway, California Highway Patrol Officer Daniel Hill said. She was trying to cross the westbound lanes of I-580, near MacArthur Boulevard and High Street, about 4:45 a.m. when she was hit by a Chevrolet Silverado, Hill said.

The driver of the truck told police he saw the woman coming and tried to avoid her but that she appeared to run directly at the truck, Hill said.

"It does not appear he did anything wrong," Hill said.

No arrests were made, and the driver was not injured.

The woman was pronounced dead at the scene after emergency workers tried to revive her, Hill said.

The CHP closed the two far left lanes of the freeway about 5 a.m. to investigate. The lanes reopened at 6:15 a.m., and traffic started to move more freely through the area shortly afterward.

Police are still investigating and are asking anyone who may have witnessed the collision to call the CHP's Oakland office at 510-450-3821 or 800-835-5247.

Contact Rick Hurd at 925-945-4789. Follow him at Twitter.com/3rdERH.