Night Of The Comet (1984; full)

Earth is passing through the tail of a comet, an event which has not occurred in 65 million years and coincided with the extinction event that wiped out the dinosaurs.

Reggie helps her boyfriend Larry sneak back in so he can loan out a film reel; He plans to pay for her assistance from what he expects to earns. Reggie's sister Sam argues with their stepmother Doris; This escalates to a physical altercation and Sam spends the night in a steel backyard shed. The next morning there are piles of red dust and heaps of clothing everywhere. Larry goes outside and is killed by a zombie. Reggie looks for Larry outside and runs into the zombie and escapes on Larry's motorcycle. She finds her sister who surmises that because they both spent the night in steel containers they were saved.
They come across another survivor, Hector. When Sam talks into the microphone, she is heard by researchers in an underground installation out in the desert. Hector leaves to check if any of his family survived, but promises to return as soon as possible. Reggie and Sam then go shopping at a mall where the girls are taken prisoner; They are saved by the scientists. Audrey White euthanizing Sam by injecting her with only a sedative and kills the other remaining scientist. When Hector returns Audrey briefs him on the situation and then gives herself a lethal injection; The pair then set out to rescue Reggie.
The researchers had suspected and prepared for the comet's effects, but left the ventilation system open and the fans running during the comet's passage. Reggie escapes and discovers that the dying scientists have hunted down and rendered healthy survivors brain-dead to harvest untainted blood to keep the disease at bay while desperately searching for a cure. Reggie saves a young boy and a girl before they are processed, then blow up the scientists.
Reggie pairs up with Hector, and they assume parental roles with the kids. Sam ignores Reggie's warning about crossing against the still-operating signal light and is almost run over by a sports car driven by Danny Mason KEENER, WHO invites her to go for a ride.

Cast
Catherine Mary STEWART; Regina "Reggie" BELMONT
Kelli MARONEY as Samantha "Sam" BELMONT
Robert BELTRAN as Hector GOMEZ
Sharon FARRELL as Doris BELMONT
Mary WORONOY as Audrey WHITE
Geoffrey LEWIS as Dr. CARTER
Peter FOX as Dr. WILSON
John ACHORN as Oscar
Michael BOWEN as Larry DUPREE
Devon ERICSON as Minder
Lissa LAYNG as Davenport
Janice KAWAYTE as Sarah
Chance BOYER as Brian
Ivan E. ROTH as Willy
Dick RUDE and Chris PEDERSON as Stockboys
Marc POPPEL as Danny Mason “DMK” KEENER DMK