Gate (Motion picture : 1987)

"Haunting visions fill a once-peaceful home as two teens discover an unholy evil that awaits below--they've unlocked deadly demons and ghoulish fiends out to create a Hell on earth."@en
"The removal of an old tree in Glen's backyard reveals a large and mysterious hole. Glen and his sister, Al, are left to look after themselves for three days when their parents go away. This is when strange things begin to happen, all of them centered around the "hole"."
"The removal of an old tree in Glen's backyard reveals a large and mysterious hole. Glen and his sister, Al, are left to look after themselves for three days when their parents go away. This is when strange things begin to happen, all of them centered around the "hole""@en
"After an old tree is removed from the ground, three young children accidentally release a horde of nasty, pint-sized demons from the hole in a suburban backyard. What follows is a classic battle between good and evil as the three kids struggle to overcome a nightmarish hell that is literally taking over the Earth."@en
"Fantasy and reality combine when two adventurous young teenagers dig up the ghoulish, evil forces of a time long past ... from a hole in their own backyard."@en