More details have been released regarding Thursday night's fatal theater shooting in Louisiana, which left three people dead, including the gunman, and nine people injured.

The shooter has been identified as 59-year-old John Russell Houser. Police say he opened fired inside of a movie theater at the Grand Theatre 16 in Lafayette during the 7:10 p.m. screening of Amy Schumer's new movie "Trainwreck." After watching the film for 20 minutes, Houser fired 13 rounds with a .45-caliber handgun and killed the two people sitting in front of him, reports ABC News. Houser shot himself as police arrived on the scene.

"A lot of the people thought it was part of the film," witness Josh Doggett told NBC Los Angeles. Doggett said there was a pause after the initial shots, but when the firing resumed, "everyone started climbing over the seats."

"In the top left of the theater was a man shooting. He was kind of a middle-aged gentleman in a polo shirt. He wasn't erratic or nervous ... just walking down the aisle, randomly firing."

Jalen Fernell was another witness in a neighboring theater. Fernell said she heard "three pops, then ... about 10-15 seconds later the sirens went off and the PA system told everyone to evacuate the building."

Lafayette Police Chief Jim Craft described the shooter as "kind of a drifter" from Alabama. Houser had been living in a local Motel 6 in Lafayette since early July.

Police said the gunman was "estranged" from his family, but a motive has yet to be determined.

Authorities have found various "disguises, basically," including wigs and glasses at the hotel room where Houser had been staying, which indicate that he originally intended to flee the scene.

"It is apparent he was intent on shooting and escaping" before he shot himself to death, said Craft, reports CNN. "The quick law enforcement response pushed him back into the theater," Craft said at a news conference, adding that the gunman's car was positioned near the exit.

The two victims are Mayci Breaux, 21, of Franklin, Louisiana, who died at the theater, and Jillian Johnson, 33, of Lafayette, who died after being transported to a hospital. One of the wounded is currently in critical condition.