The tanker cars that were part of an oil train that derailed in West Virginia Monday were newer models that included safety upgrades voluntarily adopted by the industry four years ago. 

Train company CSX confirmed Tuesday that the cars were CPC 1232 models. An estimated $7 billion has been spent to put 57,000 of these cars into service, according to the Railway Supply Institute.

Now the Obama Administration is considering requiring even more upgrades, such as thicker tanks, shields to prevent tanks from crumpling, rollover protections and electronic brakes that could make cars stop simultaneously, rather than slam into each other. Some of the measures would cost billions more and have been strongly opposed by the oil and rail industries.

The train derailed Monday afternoon near unincorporated Mount Carbon just after passing through Montgomery, a town of 1,946, on a stretch where the rails wind past businesses and homes crowded between the water and the steep, tree-covered hills. The train was carrying more than 3 million gallons of North Dakota crude oil and was bound for an oil shipping depot in Yorktown, Va.

The derailment resulted in the evacuation of hundreds of families as 19 cars slammed into each other and caught fire, leaking oil into a Kanawha River tributary and burning down a nearby house. The area lost its drinking water and electricity, and fire crews said Tuesday they had little choice but to let the cars burn themselves out. Each car carries up to 30,000 gallons of crude.

By Tuesday evening, power crews were restoring electricity, water treatment plants were going back online, and most of the local residents were back home. Initial tests showed no crude near water plant intake points, state Environmental Protection spokeswoman Kelley Gillenwater said.

"There's nothing there," said Sen. Joe Manchin, D-W. Va., who toured the scene. "All you can see is a couple of blocks sticking out of the ground. There's some pickup trucks out front completely burned to the ground."

One person -- the homeowner -- was treated for smoke inhalation, but no other injuries were reported. The two-person crew, an engineer and conductor, managed to decouple the train's engines from the wreck behind it and walk away unharmed.

The National Transportation Safety Board (NTSB) said its investigators will compare this wreck to others, including one that occurred last year when three cars plunged into the James River near Lynchburg, Va., and one near Casselton, N.D., when a Bakken crude train created a huge fireball that forced the evacuation of the farming town.

"This accident is another reminder of the need to improve the safety of transporting hazardous materials by rail," said Christopher Hart, NTSB's acting chairman.

Snow was falling heavily Monday -- as much as 7 inches in some places -- but it's not clear if weather was a factor. All but two of the 109 cars were tanks, and 26 of them left the tracks.

No cause has been determined, said CSX regional vice president Randy Cheetham. He said the tracks had been inspected just three days before the wreck.

"They'll look at train handling, look at the track, look at the cars. But until they get in there and do their investigation, it's unwise to do any type of speculation," he said.

If approved, the increased safety requirements now under White House review would phase out tens of thousands of the older tank cars being used to carry highly flammable liquids, and require more recently retrofitted cars to have new upgrades.

Sen. Manchin and Gov. Earl Ray Tomblin deferred questions on safety Tuesday, saying it's largely up to federal officials. But the state does have a say over some safety variables, such as public disclosure.

Railroads are required by federal order to tell state emergency officials where trains carrying Bakken crude are traveling. CSX and other railroads called this information proprietary, but more than 20 states rejected the industry's argument, informing the public as well as first-responders about the crude moving through their communities.

West Virginia is among those keeping it secret. State officials responded to an AP Freedom of Information request by releasing documents redacted to remove nearly every detail.

There are no plans to reconsider after this latest derailment, said Melissa Cross, a program manager for the West Virginia Division of Homeland Security and Emergency Management.

Shipments of oil by rail jumped from 9,500 carloads in 2008 to more than 435,000 in 2013, driven by a boom in the Bakken oil patch of North Dakota and Montana, where pipeline limitations force 70 percent of the crude to move by rail, according to American Fuel and Petrochemical Manufacturers.

The downside: Trains hauling Bakken-region oil have been involved in major accidents in Virginia, North Dakota, Oklahoma and Alabama, and Canada, where 47 people were killed by an explosive derailment in 2013 in Lac-Megantic, Quebec.

Reports of leaks and other oil releases from tank cars are up as well, from 12 in 2008 to 186 last year, according to Department of Transportation records reviewed by The Associated Press.

Just Saturday -- two days before the West Virginia wreck -- 29 cars of a 100-car Canadian National Railway train carrying diluted bitumen crude derailed in a remote area 50 miles south of Timmins, Ontario, spilling oil and catching fire. That train was headed from Alberta to Eastern Canada.

The Associated Press contributed to this report.