He’s one twisted monster.

Dimitrios Pagourtzis war-whooped “Woo-hoo,” blared a WWII Japanese military anthem on his phone and shouted cruel taunts as he opened fire on his cowering classmates, according to new accounts a day after the Texas high school junior allegedly killed eight students and two teachers.

The admitted gunman even chillingly sang “Another one bites the dust!” as he fired away with his father’s Remington 870 shotgun and .38-caliber handgun.

“My friend Trent was in the classroom and said after [Pagourtzis] would shoot a student he would sing, ‘Another one bites the dust!’” Sante Fe High School sophomore Kole Dixon, 16, told The Post of a classmate, whose last name he asked not be printed.

“He also kept playing a kamikaze song over and over as loud as he could,” on his cellphone, Dixon said of the shooter.

Pagourtzis had the same kamikaze military anthem on his now-deleted YouTube page, Dixon said.

Pagourtzis had earlier bragged of wearing a “Rising Sun” insignia on his black trench coat, explaining it signified “Kamikaze Tactics,” according to a photo and text posted on his also-deleted Facebook page.

New details of the 17-year-old’s sick sense of humor went well beyond the previously reported “Born to Kill” T-shirt he wore, and his taunt of “Surprise!” as he blasted through the walls of an art class supply closet.

“They hear the gunman in the classroom next door yelling Woo Hoo! and firing more shots,” mom Deedra Van Ness said in a Facebook post Friday night, recounting details from her by her daughter Isabelle, who survived unscathed but was covered in blood.

“Surprise, motherf–ker!” the shooter hollered as he fired into the closet wall, instantly killing two of the half-dozen students who had barricaded themselves inside with Isabelle, Van Ness said her daughter told her.

“Are you dead?” he later asked from the other side of the closet.

“Do you think it’s for you?” he also joked, as cell phones left behind in the classroom rang unanswered.

County officials revealed that Pagourtzis exchanged “a lot of firepower” with authorities before surrendering. Despite this alleged show of firepower, Pagourtzis purposefully collapsed while giving himself up — so he wouldn’t be shot by his arresting officers. The shooter, “sort of fell to the ground and surrendered,” said Republican Texas Rep. Michael McCaul.

So-called “explosive devices” found in the school and in Pagourtzis’ car and home were duds — incapable of detonating, Texas officials said. The devices included carbon dioxide canisters tapped together, and a pressure cooker with an alarm clock and nails inside.Source: Texas school shooter taunted victims during rampage: witnesses