FAIRFAX, Va. -- With the rise of gas prices the popularity of hybrid vehicles is growing, but rescue crews say the cars pose a risk if they're in an accident.

Under the hoods of those cars, and in the trunk there are warning signs the driver may not know about.

Bob Rogers with State Farm Insurance told News4's Jim Handly, "Some of these vehicles have charges that exceed 500 volts and obviously 500 volts can be fatal."

Officials say rescue crews face challenges in extricating occupants from a hybrid vehicle. Before a trapped victim can be cut out, trained eyes must check for critical markings, and from the outside it can be tricky.

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During a training exercise involving hybrid cars, Matt Groff with the Fairfax County Fire Department said the Ford hybrid Escape looks the same as the regular gas vehicle, and so do some of the Hondas.

So first responders are trained to look for warning flags on the inside of the cars. On the Ford, there's a bright orange coil around the high-voltage cable that runs under the carriage of the car from the trunk to the engine.

"If we see anything orange and we're about to cut into or work around it, that gives us the red light that we need to avoid that completely," Groff said. "When we respond to an accident, we go through a process of de-energizing or controlling that energy back to the battery pack. We can never get rid of that energy in the battery pack, but we can isolate it."

And officials say the most dangerous point in a hybrid vehicle is the battery pack located in the rear of the vehicle.

"Some of the accidents that we run are horrific, and if that battery pack is split open we definitely have a shock hazard as well as a small hazardous-materials problem, Groff said.

There are other new technology hazards in the hybrid and non-hybrid cars that officials say could pose a risk in an accident, like undeployed airbags on all sides and power seat belt pretensioners.

Groff said, "If these pretensioners haven't fired and there is an extrication process the fire departments will need to know where they are located on different vehicles because they can become flying missiles during an extraction."

But perhaps one of the first uncertainties facing responders arriving at an accident scene is whether the vehicle is running. Officials said there is not much to hear on a hybrid car, so rescue crews are trained to look for a ready indicator light.

Groff said one of the first things crews are trained to do is to make sure the ignition is shut down.

Automakers have worked with first responders and put many safeguards in place. Toyota, maker of the popular Prius, issued the following statement.

"The high voltage batteries are contained in an extremely strong steel protective case. In the event an abnormal condition is detected, all high voltage circuits are disabled and high voltage is contained inside the protective case. High voltage cables are heavily insulated, shielded and isolated."