MISSOULA, Mont. -

Missoula is mourning the death of a popular Hellgate High School senior killed when he was hit by a car Monday afternoon.

Chance Geery was walking on the sidewalk with his girlfriend when a woman's car left Mullan Road and struck him. The 18-year-old was pronounced dead at St. Patrick Hospital.

As investigators try to piece this tragic, strange case together, friends can't believe the kid who made everybody laugh is gone.

Chance Geery was a Hellgate Knight football player. He wanted to play for the Griz, said his mom. He would have graduated in June.

"He was my brother," said a Knight teammate, "there's nothing we can do but pray. We loved him."

Investigators are still trying to figure out what happened.

"Looking at the scene, gathering evidence, talking to anybody that might have some idea of what occurred moments before the impact," said Detective Sergeant Travis Walsh from the Missoula Police Department.

Investigators ruled out alcohol, drugs and cell phones. Welsh said it doesn't appear excessive speed is an issue. But he said so far I don't know how fast the driver was going.

He said the driver has been very cooperative. As of yet, no charges have been filed.

Nearby workers heard the crash.

They said they heard a loud bang, but no brakes, and a girl screaming. "He got hit," she said. "He got hit. He's my boyfriend."

Kaitlin Patton and Rebecca Parrish were classmates of Chance's going all the way back to sixth grade at Bonner School.

"He was the class clown," said Patton. "He was happy all the time. He was always goofing off."

"I can't believe he's dead," said Parrish. "He was a sweetheart. We've known him since sixth grade."