COLORADO SPRINGS, Colo. -- An 18-year-old woman burned to death Tuesday after a chain-reaction crash caused a pickup truck to run into a gas pump at a convenience store in Colorado Springs, triggering an explosion and fire that engulfed her and her minivan.

The woman was outside of her minivan, pumping gas at a 7-Eleven store at about 12:40 p.m. when a sport utility vehicle drove into the back of a pickup, pushing it into the gas pump, witnesses told 7NEWS.

The pump was knocked to the ground and exploded, sending a huge fireball into the air. The woman was pinned between the burning gas pump and her minivan. Witnesses ran up to help but were powerless to pull the woman out of the towering flames.

"When I came up she was standing there screaming, 'Help me! Help me! I'm going to die,'" said witness Allen Pitts.

"She was frozen in there, between the gas pumps and her car," witness Michael Horvat told the Colorado Springs Gazette. "She was holding her face. Flames were all around her. She never got out."

Police identified the victim as Whitney Hendrickson, of Colorado Springs. She was home on spring break from Grinnell College in Iowa.

Hendrickson was a freshman at Grinnell. Her friend Julie Podair, a Grinnell student from Appleton, Wis., was in the minivan but escaped without injury.

Horvat said he works across the street and when he heard the crash, he ran over with a fire extinguisher, but an off-duty firefighter told him to get back as the gas pump island erupted in flames.

Jon Massey, who also works across the street, captured pictures of the dramatic explosion. Pushed back by intense heat, he and others watched as the screaming woman remained trapped in the flames.

"I am definitely shaken up a little. You never know what's going to happen. Another reminder of how fragile life is. My heart goes out to the victim's family," Massey said.

Pitts, an Iraq veteran, said the sight and smell brought back memories of war.

"It reminded me of being in Iraq again, you know. I tried to get as close as I could but at that point the car exploded and you know, just the smell reminded me of Iraq," Pitts said.

Police officers are looking into the cause of the crash, but witnesses believe that it was triggered by a woman driving a Ford Explorer.

The Explorer was going through the parking lot when it struck the right rear side of a Chevrolet Silverado pickup truck that was parked at the gas pumps facing west, police said.

"The impact forced the truck into the gas pump, which dislodged it from its base, at the same time rupturing the fuel pumping system and spilling some gasoline onto the ground. The gas pump then fell ... trapping a woman who was at that moment fueling her vehicle. She was standing between her 2000 Honda minivan that was parked facing east, and the pump. At some point in the sequence of events, the fuel that was spilled ignited, causing the ensuing fire," Colorado Springs police Lt. David Whitlock said.

The driver of the Explorer, identified as 20-year-old Kelli Renae McKay, was transported to Memorial Hospital where she was treated and released for minor contusions. McKay was cited with careless driving involving death, a misdemeanor. She was served and released on a summons to appear in El Paso County Court for those charges.

Pitts and others heard McKay saying her brakes had gone out but Whitlock said that there was no evidence that any vehicle malfunction was a contributing factor in the crash. Alcohol and drugs were not suspected either, Whitlock said.

The explosion occurred on West Colorado Avenue and 15th Street, but could be seen blocks away.

"I heard a crash, so I jumped up and ran outside of my building. I noticed an SUV had crashed into one of the gas pumps across the street and people were running and screaming. All of the sudden, I heard an explosion and the minivan was engulfed in flames. It was one huge fireball. I immediately dialed 911 and the fire department was on the scene within minutes. While on the phone with 911, I could hear additional gas explosions," Massey said.

"I live about a half-block away and I was sitting on my porch talking to my friend and I overheard a crash. As I stood up I could see the 7-Eleven from my front porch ... and I could see 30- to 40-foot-high flames and black smoke spewing everywhere," Pitts said.

Firefighters arrived within a minute of the initial call but could do little to help.

"They were only a few blocks away and they were in there, maybe about two to three minutes, but by that time, it was over in 45 seconds," Pitts said.

Update: The driver that caused the wreck won't face felony charges. Read the latest here.