An explosion and fire ripped through a Shell Oil Co. refinery Thursday, leaving one person dead, 33 injured and five missing and forcing 2,800 residents to evacuate, officials said.

The blast was so powerful it broke windows and set off burglar alarms 20 miles away, and Shell spokeswoman Sarah Coletti said both plant workers and neighborhood residents were injured."My layaway bins are in the back yard. The back door where we process shipments is completely blown off. There's daylight all over the building," said Gloria Estillette, manager of a nearby store smashed by the blast.

The blast occurred at a catalytic cracker, which converts crude oil to gasoline, but no cause was known, Coletti said. The fire was brought under control 5 1/2 hours after the 3:30 a.m. explosion but continued to burn.

"It looks like there is something on the ground that is burning. It doesn't seem to burn out," said Jimmy Greco, riding in a medical helicopter 1,000 feet over the scene.

The blaze cast an eerie glare across the isthmus between the Mississippi River and Lake Pontchartrain 20 miles upriver from New Orleans. Thick, acrid smoke billowed over the area, looking like thunderclouds in the red glow.

The force of the blast blew out windows. The entire metropolitan area was shaken awake as the rattling explosion set off burglar alarms and broke plate glass windows.

Hospital officials said 33 people were injured, including at least 19 community residents. Shell spokesman Phil Schwin said five people were unaccounted for.

Schwin said damage went into the millions, including damage at the main shop and control rooms. A small fire burned in the distilling unit.

"I've never seen so much damage in Norco, even when hurricanes have hit," said Ikey Lucas, director of St. Charles Parish Emergency Operations.

The area from Norco downriver to the Bonnet Carre Spillway was ordered evacuated by a special emergency operations office, affecting about 2,800 people, officials said.

An evacuation center was set up at Destrehan High School, but officials allowed everyone to return home after 9 a.m. except those living on the two streets next to the refinery.