The kerosene bombs that killed nearly 70 aboard a highly symbolic India-Pakistan train Feb. 18 have sparked new worries among U.S. law enforcement authorities, who noted the success of the cheap, lethal, easy-to-make-and-deploy terror device, ABC News has learned. Two suitcases packed with plastic kerosene bottles, planted by exits and triggered by a low-explosive, timed black powder fuse sent tongues of intense flame licking through one rail car aboard the Friendship Express in that militant attack. Only the fact that two others placed in another car failed to ignite prevented further casualties aboard the train put into service between India and Pakistan in 2004. U.S. authorities and private intelligence firms have expressed concern that the devices could supplant more complex improvised high explosive devices as a terrorist bomb of choice and that they could be used on U.S. subway and commuter rail lines, according to law enforcement sources and written reports. The successful use of a tactic by terrorists and militants in one sphere of operations has frequently led to the use of similar tactics in other areas of conflict. Most recently, in Iraq, this has been seen in the use of armor-piercing charges that use molten projectiles to maximize damage. Similar charges were used in both Lebanon and Afghanistan, among other conflict zones. The private intelligence forecasting firm, Strategic Intelligence Forecasting, noted on Feb. 19 that the attack "portends similar attacks against India’s highly vulnerable mass transit system by militants. Moreover, the use of TIDs (Timed Incendiary Devices) easily could spread elsewhere." "High concept, low technology, that’s the most scary," said one northeast U.S. emergency management official. In New York last year, authorities devoted one mass transit rescue drill to a scenario that involved removing numerous victims from a regional commuter line that had been wrought by explosions and the spread of chemical gases. Sources tell ABC News that following the India-Pakistan attack, U.S. authorities in at least some other urban areas recommended that emergency response teams incorporate knowledge of the devices into future training regimes. Strategic Intelligence Forecasting noted that the India-Pakistan attack "sets a potentially dangerous precedent, especially since TIDs can be more easily constructed, and with more readily available materials, than more complex high-explosive IEDs. This type of attack likely will be copied elsewhere in India, and beyond." "Explosive-actuated TIDs, more commonly called firebombs, work by using a relatively small low-intensity explosive charge to ignite a more volatile flammable material. This results in an intense, rapidly spreading fire that quickly can engulf a confined space such as a rail car, subway car or airplane," the brief stated. Similar attacks were unsuccessfully attempted on trains in Germany in August 2006. The devices used in those plots failed to ignite.