BENICIA, Calif. (AP) — Local and state leaders are raising concerns about a San Francisco Bay Area refinery’s plan to move as many as 100 train cars of flammable crude oil daily through Northern California cities.

The Sacramento Bee reports the Valero Refining Company in Benicia plans to have trains travel on the Union Pacific line that runs through downtown West Sacramento and Davis, along the same tracks that carry Capitol Corridor passenger trains between Sacramento and the Bay Area.

The Benicia refinery currently gets most of its crude from pipelines and ships. But Valero and many other refineries also intend to rely more on rail shipments to align with the boom in hydraulic fracturing, or fracking, in areas such as North Dakota’s Bakken oil fields.

“These rail shipments are the wave of the future,” Sacramento city official Fran Halbakken said. “But there is not much information out there.”

Valero Energy spokesman Bill Day said it would allow the refinery to buy at least half of its crude oil from North American sources. The refinery has a pending application to build a rail terminal with the City of Benicia. Once it clears environmental review, the company plans to move forward.

“We’re working with our rail partner to make this the safest possible system that we can (get),” Day said. “This will allow us to replace deliveries by ship, which would increase energy independence of the refinery.”

Crude-oil shipments into California via rail from other states jumped from 1 million barrels in 2012 to more than 6 million in 2013, according to data compiled by the California Energy Commission.

In addition to Valero, Phillips 66 said it plans to begin deliveries of crude by rail next year to its refinery in Santa Maria. Union Pacific intends to deliver up to five 80-car trains of oil “from a variety of sources in North America” each week.

Sacramento officials are preparing to write a joint statement to Valero seeking additional details. They also will write to propose how to increase safety in cities along the route to the company’s planned rail terminal next to Interstate 680, just north of the Benicia-Martinez Bridge.

Later this month, Valero and Benicia officials are expected to publish a draft environmental impact report on the rail terminal, and the Sacramento Area Council of Governments also will meet to discuss the issue.

Sacramento Democratic Rep. Doris Matsui has also expressed concerns about the potential for accidents and spills, and she recently has sought additional federal funding for first-responder training from the U.S. Department of Homeland Security.

Last July, a runaway train with 72 tankers of oil derailed and exploded in the small Quebec town of Lac-Megantic near the Maine border, destroying the town’s center.

While such accidents appear relatively rare, her office issued a statement this week saying “it is imperative that the rail cars are safe and that local agencies are prepared for the increased risk.”