July 10, 2001 11:00 pm

By The Observer

A leaking tank of a chemical often used in the manufacture of methamphetamine and a second tank rapidly heating inside a burning car posed the threat of burns, corrosive vapors, injuries and possible explosion to rescue workers and passing motorists along Interstate 84 eastbound Tuesday morning.

Three people who had been inside the car were injured, two with serious burns over large portions of their bodies and one with unidentified injuries, according to Oregon State Police reports.

The saga began shortly after 5 a.m. when a Nissan 300SX driving eastbound near milepost 267, three miles south of the Highway 203 interchange, became engulfed in chemical vapors. One of the two five-gallon propane tanks in it, containing anhydrous ammonia, had apparently ruptured, police said.

According to the North American Emergency Response Guidebook, the vapors of anhydrous ammonia are extremely irritating and corrosive and can be fatal if inhaled.

Anhydrous ammonia is a chemical used for fertilizer and is also, according to the Oregon State Police, often used in methamphetamine labs.

The driver of the Nissan, identified as Mandy Cranner, 19, of Fruitland, Idaho, stopped the car and fled the area before any help arrived. State police believe she got a ride from an unknown person into La Grande. Cranner was found at Grande Ronde Hospital.

Armand Macy, 21, of Baker City, and Justin Cooper, 20, of Ontario, were found near the burning car and taken by ambulance to Grande Ronde Hospital. They were then taken by LifeFlight to Emanuel Hospital in Portland with burns over large parts of their bodies, according to a hospital spokeswoman.

Emergency services personnel closed the interstates eastbound lanes at about 6 a.m. and kept them closed until just before 9 a.m., diverting traffic headed toward Baker City to Union.

Because of the unstable and hazardous nature of anhydrous ammonia, a HazMat team from La Grande was called to the scene, along with Oregon State Police, firefighters and Union County Sheriffs deputies.

Since one of the two tanks had already ruptured, officers, fearing the second tank might rupture or explode, used a shotgun to penetrate the second tank.

Putting a hole in the second tank allowed the anhydrous ammonia to drain out without erupting. The guidebook states that anhydrous ammonia cylinders may explode when heated but that they dont ignite easily.

The interstate reopened when the tanks had been cooled, the vapors cleared and the tanks properly removed.

State police and the Union County multi-agency drug task force are investigating what Macy, Cooper and Cranner were doing with the anhydrous ammonia in the car.