A Casper man was arrested Wednesday afternoon after allegedly threatening to shoot his sister's new partner and "everyone in the room."

Colton Eric Wagner, 21, was booked into jail on a charge of aggravated assault and battery. He will likely make his initial appearance in Natrona County Circuit Court on Wednesday afternoon.

Court documents say just before 1:30 p.m. Wednesday, a Casper police officer went to the home on Oleander for a reported weapon offense.

A teenage girl had called 911 and said Wagner was at the residence with a gun, and was threatening to "shoot everyone." The girl said she and three others were locked in a bedroom, and Wagner was banging on the door.

The officer arrived and immediately heard loud banging from the southeast corner of the residence. He approached the front door and heard loud footsteps on the stairs near the door.

The door was locked, so the officer began to kick the front door. But after two kicks, the officer heard loud footsteps on the stairs, someone slam into the door and the sound of someone apparently fiddling with the door handle.

The officer backed up along the side of the house, and a man came out of the home with his hands in the air. The officer ordered the man, later identified as Wagner, to lay down on his stomach. Wagner allegedly resisted the officer's attempt to handcuff him, but Wagner was taken into custody. The officer found brass knuckles and keys in one of Wagner's pockets, but no gun.

Everyone inside the house -- three juvenile teens and three 18- or 19-year-olds -- said Wagner had a gun, but they didn't know where it was.

Through interviews with those teens, police learned that one of the teens was dating Wagner's sister, and Wagner was upset about it. Wagner had allegedly been threatening the teen for some time, becoming increasingly unstable.

On Tuesday, the day before his arrest, Wagner reportedly showed up to the house with a gun in his waistband. He never pointed it at anyone, one witness said, but Wagner allegedly said, "look what I have."

Witnesses said on Wednesday, Wagner showed up with the black gun in his right hand and walked  down to the basement, where his sister, her partner and two others were hanging out.

Wagner allegedly threw open the door to a bedroom basement and pointed a handgun at his sister's partner, then waved the gun around at everyone in the room before briefly leaving the room. When Wagner stepped out, one of the teens closed and locked the bedroom door.

Wagner reportedly returned and banged on the door, threatening to shoot everyone. Wagner's sister called 911 and, a short time later, Wagner ran upstairs and everyone found that a police officer had arrived.

In a cabinet beneath the kitchen sink, police reportedly found a .40-caliber Glock 27. Nine rounds were in the gun's magazine, with one round in the chamber.

The homeowner arrived later and said she had an "open door" policy for her home, allowing her children's homeless friends to stay in the house, court documents say. She also reportedly said she had allowed Wagner to use her grey Chevrolet Impala.

A search of the Impala allegedly turned up one 50-round box of .40-caliber ammunition. The box was missing 10 rounds.