GOLDEN, Colo. -- A videotape of the Columbine High School gunmen laughing and shooting at trees and bowling pins six weeks before they killed 12 classmates and a teacher was released to the public Wednesday.

"Imagine that in someone's (expletive) brain," Eric Harris says.

The tape of Harris and Dylan Klebold, who committed suicide after the rampage on April 20, 1999, shows at least four weapons, including automatic rifles, shotguns and a pistol.

Clad in a trenchcoat, Klebold at one point holds a sawed-off shotgun and shoots from the hip at a bowling pin wedged between two tree limbs. He and Harris then look at a bullet-shredded tree trunk.

The homemade tape was released at the urging of the Jefferson County Sheriff's Office and a task force established by the attorney general's office, both of which want to make evidence in the case public.

The sheriff's office earlier released surveillance video showing the teenagers as they entered the high school cafeteria during their rampage.

Randy Brown, a member of the task force, said he and his wife warned sheriff's deputies more than a year before the shootings that Harris had threatened to kill one of their sons.

"The videotape is important," Brown said. "What's really important is did the sheriff see it, did the school see it, or did the parents see it? How many opportunities were missed to stop these two killers?"

Also on the tape were Philip Duran and Marc Manes, both of whom were charged with providing the teens with guns. The men were in their 20s at the time of the shootings.

Duran was sentenced in June 2000 to 4 1/2 years in prison; Manes was sentenced in 1999 to six years in prison.