Some time later, four teenagers, Tom, Greg, Beth and Sandy, hike in the same area, ignoring the warnings of local truck stop owner Joe Taylor.

A group of Cub Scouts is also in the area; their leader is also killed by the alien creatures, while his troop runs into an unidentified humanoid and flee.

The sheriff arrives, but since they have just postulated that the alien could disguise itself as human, Sarge shoots at what he thinks is an invader, only to realise the truth a few seconds too late; his shock at what he has done first horrifies him, then his mental illness causes him to start blaming Greg.

While the locals telephone for an ambulance, Greg and Sandy leave with Taylor, who says they need proof to convince the authorities to act, as everyone already thinks that the only other person who believes in the creatures, Sarge, is crazy.

They search for the shack and once there, Taylor goes inside and finds the bodies of Tom, Beth, the father and son, and the cub scout leader.

Greg plays along, telling the deranged man that an invasion force is on the way, thus distracting him enough to toss him aside, run away with Sandy and jump from a bridge.

Grodnik sat down in his living room on an IBM typewriter on top of a TV tray table and finished the script.

Because Tramer was trying to break into the comedy writing business he felt putting his name on the film wasn't a good idea so he asked to be credited as Ben Nett.

Grodnik explained to Tramer, who had no credits at the time, that even the great director Robert Wise, who directed The Sound of Music and West Side Story started off with a horror film entitled The Curse of the Cat People, and that didn't hurt his career but Tramer was adamant that the film credit him as Ben Nett.

Tom Buckley of The New York Times wrote: "The big moments, such as they are, in Without Warning have been borrowed from Alien and Invasion of the Body Snatchers.

[8] DVD Talk recommended the movie, writing "Without Warning may not be a lost masterpiece but it is a really entertaining low budget horror picture that makes the most of its effects set pieces and a few notable cast members".

Club praised the performances of veteran actors Martin Landau and Jack Palance and called some of the special effects "damn gross".