Tenn. movie theater attack has police asking "Why?"

Members of The Nashville Fire Department and Metro Police enter Hickory Hollow Cinemas on August 5, 2015 in Antioch, Tennessee.

Jason Davis, Getty Images

Investigators are trying to determine why a 29 year-old man with a history of mental illness viciously attacked a group of people inside a movie theater in Tennessee, reports CBS News correspondent David Begnaud.

Vincente Montano bought a ticket at the Carmike Hickory Cinema Wednesday afternoon, authorities said. He went inside one of its eight theaters to a showing of "Mad Max: Fury Road."

Axe-wielding man shot dead at Tennessee movie theater

"He pulled out, like, a hatchet and started attacking this family and then he pulled out a gun and we all ran out of the theater," one person said to 911 dispatch

Metro Nashville police say Montano entered the cinema wearing a surgical mask, toting a pellet gun and a hatchet. He clouded the room with pepper spray before swinging the blade at a man and his daughter.

"All of the citizens who gathered around us helped my daughter when we were pepper sprayed," the father, Steven, said. "That kind of gives me a little more faith in humanity again."

Three people suffered minor injuries.

Police say a suspect was carrying this axe at a suburban Nashville theater as he released pepper spray there. He was shot and killed by police shortly after after exchanging fire. Metro Nashville PD

When Montano tried to leave through the theater's back door, he was met by a SWAT team.

"There was a noise made by that gun and it was then that the officer fired," police spokesman Don Aaron said said.

A witness captured the loud gunshots heard during the SWAT team's take-down.

A bomb squad then detonated Montano's backpack.

"The things that were put into that duffle bag, backpack were put in there to resemble a hoax explosive device," Aaron said.

The 29-year-old attacker died at the scene, rolled away on a gurney.

A photo released by Metro Nashville police shows Vincente David Montano. Metro Nashville PD

Just two days before the attack, his mother, Denise Pruett, filed a missing person's report with Murfreesboro, Tennessee, police.

The report says Montano was diagnosed with paranoid schizophrenia in April 2006. Pruett told police she hadn't seen her son since 2013.

"It sent chills, just chills through my whole body," neighbor Dorethea Cummings said.

She lived next door to Montano for a decade and told CBS News police were regularly called to the house.

"He was highly agitated, he was pacing back and forth, so this went on for several hours," she said.

Montano was charged with assault on a Murfreesboro police officer and resisting arrest in September of 2004. He was committed twice that year and two more times in 2007.

This attack comes just two weeks after two women were killed by a gunman inside a theater in Lafayette, Louisiana.